Experiments were designed to unravel the relative contribution of beta 1- and beta 2-adrenoceptors to the positive inotropic effects of adrenaline and noradrenaline in isolated tissues of left ventricular myocardium of man. We also analyzed relationships between the fractions of human left ventricular beta 1- and beta 2-adrenoceptors, estimated from binding assays, and stimulation of adenylate cyclase and contractile force by adrenaline and noradrenaline. Selective blockade of beta 2-adrenoceptors by erythro-(+/-)-(alpha-methyl-indan-4-yloxy)-3-isopropylaminobuta n-2-ol (ICI 118,551) attenuated the increase of contractile force caused by adrenaline but not by noradrenaline, suggesting some involvement of beta 2-adrenoceptors. Selective blockade of beta 2-adrenoceptors without affecting beta 1-adrenoceptors still enabled both adrenaline and noradrenaline to cause maximum possible increases of contractile force through beta 1-adrenoceptors. A direct involvement of beta 2-adrenoceptors became manifest by selectively antagonizing beta 1-adrenoceptors by 1-[2[3-carbamoyl-4-hydroxy)phenoxy)ethylamino]- 3-[4(1-methyl-4-trifluoromethyl-2-imidazolyl)phenoxy]-2-propanol (CGP 20712 A) without affecting beta 2-adrenoceptor. beta 2-adrenoceptors can mediate half of the maximum increase of contractile force elicited by low concentrations of adrenaline and also contribute to the increase of contractile force caused by high concentrations of noradrenaline. beta-adrenoceptors were labelled in membrane particles with 3H-(-)-bupranolol in the absence (beta 1 & beta 2) and presence of 500 nmol/l CGP 20712 A (beta 2). 71% of the beta-adrenoceptors were beta 1 and 29% beta 2. Binding inhibition experiments with CGP 20712 A and ICI 118,551 yielded 74% beta 1 and 26% beta 2.(ABSTRACT TRUNCATED AT 250 WORDS)

beta-Adrenoceptors (ARs) classically mediate responses to the endogenous ligands adrenaline and noradrenaline by coupling to Gsalpha and stimulating cAMP production; however, drugs designed as beta-AR agonists or antagonists can activate alternative cell signalling pathways, with the potential to influence clinical efficacy. Furthermore, drugs acting at beta-ARs have differential capacity for pathway activation, described as stimulus trafficking, biased agonism, functional selectivity or ligand-directed signalling. These terms refer to responses where drug A has higher efficacy than drug B for one signalling pathway, but a lower efficacy than drug B for a second pathway. The accepted explanation for such responses is that drugs A and B have the capacity to induce or stabilize distinct active conformations of the receptor that in turn display altered coupling efficiency to different effectors. This is consistent with biophysical studies showing that drugs can indeed promote distinct conformational states. Agonists acting at beta-ARs display ligand-directed signalling, but many drugs acting as cAMP antagonists are also able to activate signalling pathways central to cell survival and proliferation or cell death. The observed complexity of drug activity at beta-ARs, prototypical G protein-coupled receptors, necessitates rethinking of the approaches used for screening and characterization of novel therapeutic agents. Most studies of ligand-directed signalling employ recombinant cell systems with high receptor abundance. While such systems are valid for examining upstream signalling events, such as receptor conformational changes and G protein activation, they are less robust when comparing downstream signalling outputs as these are likely to be affected by complex pathway interactions.

We tested the hypothesis that astrocytic glycogen supports axon function under both pathological and physiological conditions. Functional activity of the rat (RON) or mouse optic nerve (MON), representative central white matter tracts, was assessed electrophysiologically as the area under the supramaximal compound action potential (CAP). During aglycaemia the CAP area of rodent optic nerve persisted for up to 30 min, after which the CAP rapidly failed. Glycogen content measured biochemically during the aglycaemic insult fell with a time course compatible with its rapid degradation in the absence of glucose. Pharmacological up-regulation of glycogen content prior to the aglycaemic insult with incubation in hyperglycaemic ambient glucose delayed CAP failure, whereas down-regulation of glycogen content induced by nor-adrenaline accelerated CAP failure. Inhibiting lactate transfer between astrocytes and axons during aglycaemia, where glycogen is the only utilisable energy reserve, resulted in accelerated CAP failure, implying that glycogen-derived lactate supports function when exogenous energy metabolites are withdrawn. Under normoglycaemic conditions glycogen content decreased during high frequency axon discharge, although CAP function was fully maintained. Both prior depletion of glycogen content, or blocking axonal lactate uptake rendered nerves incapable of fully supporting CAP function during high frequency firing in the presence of normoglycaemic glucose. These results indicated that during aglycaemia and increased metabolic demand, astrocytic glycogen was degraded to form lactate, which was used as a supplemental energy source when ambient normoglycaemic glucose was incapable of meeting immediate tissue energy demands.

Biochemical studies on postmortem brains of patients with Parkinson's disease (PD) have greatly contributed to our understanding of the molecular pathogenesis of this disease. The discovery by 1960 of a dopamine deficiency in the nigro-striatal dopamine region of the PD brain was a landmark in research on PD. At that time we collaborated with Hirotaro Narabayashi and his colleagues in Japan and with Peter Riederer in Germany on the biochemistry of PD by using postmortem brain samples in their brain banks. We found that the activity, mRNA level, and protein content of tyrosine hydroxylase (TH), as well as the levels of the tetrahydrobiopterin (BH4) cofactor of TH and the activity of the BH4-synthesizing enzyme, GTP cyclohydrolase I (GCHI), were markedly decreased in the substantia nigra and striatum in the PD brain. In contrast, the molecular activity (enzyme activity/enzyme protein) of TH was increased, suggesting a compensatory increase in the enzyme activity. The mRNA levels of all four isoforms of human TH (hTH1-hTH4), produced by alternative mRNA splicing, were also markedly decreased. This finding is in contrast to a completely parallel decrease in the activity and protein content of dopamine beta-hydroxylase (DBH) without changes in its molecular activity in cerebrospinal fluid (CSF) in PD. We also found that the activities and/or the levels of the mRNA and protein of aromatic L-amino acid decarboxylase (AADC, DOPA decarboxylase), DBH, phenylethanolamine N-methyltransferase (PNMT), which synthesize dopamine, noradrenaline, and adrenaline, respectively, were also decreased in PD brains, indicating that all catecholamine systems were widely impaired in PD brains. Programmed cell death of the nigro-striatal dopamine neurons in PD has been suggested from the following findings on postmortem brains: (1) increased levels of pro-inflammatory cytokines such as TNF-alpha and IL-6; (2) increased levels of apoptosis-related factors such as TNF-alpha receptor R1 (p 55), soluble Fas and bcl-2, and increased activities of caspases 1 and 3; and (3) decreased levels of neurotrophins such as brain-derived nerve growth factor (BDNF). Immunohistochemical data and the mRNA levels of the above molecules in PD brains supported these biochemical data. We confirmed by double immunofluorescence staining the production of TNF-alpha and IL-6 in activated microglia in the putamen of PD patients. Owing to the recent development of highly sensitive and wide-range analytical methods for quantifying mRNAs and proteins, future assays of the levels of various mRNAs and proteins not only in micro-dissected brain tissues containing neurons and glial cells, but also in single cells from frozen brain slices isolated by laser capture micro-dissection, coupled with toluidine blue, Nissl staining or immunohistochemical staining, should further contribute to the elucidation of the molecular pathogenesis of PD and other neurodegenerative or neuropsychiatric diseases.

The activity of phenylethanolamine-N-methyl transferase, an enzyme that synthesizes adrenaline from noradrenaline in the adrenal medulla, is markedly depressed following hypophysectomy. Enzyme activity is restored to normal after administration of ACTH or the potent glucocorticoid, dexamethasone. Thus the biosynthesis of adrenaline in the adrenal medulla appears to be regulated by the pituitary-adrenocortical system.

OBJECTIVE

cAMP is a critical messenger for insulin and glucagon secretion from pancreatic β- and α-cells, respectively. Dispersed β-cells show cAMP oscillations, but the signaling kinetics in cells within intact islets of Langerhans is unknown.

METHODS

The subplasma-membrane cAMP concentration ([cAMP](pm)) was recorded in α- and β-cells in the mantle of intact mouse pancreatic islets using total internal reflection microscopy and a fluorescent translocation biosensor. Cell identification was based on the opposite effects of adrenaline on cAMP in α- and β-cells.

RESULTS

In islets exposed to 3 mmol/L glucose, [cAMP](pm) was low and stable. Glucagon and glucagon-like peptide-1(7-36)-amide (GLP-1) induced dose-dependent elevation of [cAMP](pm), often with oscillations synchronized among β-cells. Whereas glucagon also induced [cAMP](pm) oscillations in most α-cells, <20% of the α-cells responded to GLP-1. Elevation of the glucose concentration to 11-30 mmol/L in the absence of hormones induced slow [cAMP](pm) oscillations in both α- and β-cells. These cAMP oscillations were coordinated with those of the cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) in the β-cells but not caused by the changes in [Ca(2+)](i). The transmembrane adenylyl cyclase (AC) inhibitor 2'5'-dideoxyadenosine suppressed the glucose- and hormone-induced [cAMP](pm) elevations, whereas the preferential inhibitors of soluble AC, KH7, and 1,3,5(10)-estratrien-2,3,17-β-triol perturbed cell metabolism and lacked effect, respectively.

CONCLUSIONS

Oscillatory [cAMP](pm) signaling in secretagogue-stimulated β-cells is maintained within intact islets and depends on transmembrane AC activity. The discovery of glucose- and glucagon-induced [cAMP](pm) oscillations in α-cells indicates the involvement of cAMP in the regulation of pulsatile glucagon secretion.

BACKGROUND

A reduction in salt intake lowers blood pressure (BP) and, thereby, reduces cardiovascular risk. A recent meta-analysis by Graudal implied that salt reduction had adverse effects on hormones and lipids which might mitigate any benefit that occurs with BP reduction. However, Graudal's meta-analysis included a large number of very short-term trials with a large change in salt intake, and such studies are irrelevant to the public health recommendations for a longer-term modest reduction in salt intake. We have updated our Cochrane meta-analysis.

OBJECTIVE

To assess (1) the effect of a longer-term modest reduction in salt intake (i.e. of public health relevance) on BP and whether there was a dose-response relationship; (2) the effect on BP by sex and ethnic group; (3) the effect on plasma renin activity, aldosterone, noradrenaline, adrenaline, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides.

METHODS

We searched MEDLINE, EMBASE, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles.

METHODS

We included randomised trials with a modest reduction in salt intake and duration of at least 4 weeks.

METHODS

Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regression were performed.

RESULTS

Thirty-four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt vs usual salt) was -75 mmol/24-h (equivalent to a reduction of 4.4 g/d salt), the mean change in BP was -4.18 mmHg (95% CI: -5.18 to -3.18, I (2)=75%) for systolic and -2.06 mmHg (95% CI: -2.67 to -1.45, I (2)=68%) for diastolic BP. Meta-regression showed that age, ethnic group, BP status (hypertensive or normotensive) and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic BP of 5.8 mmHg (95%CI: 2.5 to 9.2, P=0.001) after adjusting for age, ethnic group and BP status. For diastolic BP, age, ethnic group, BP status and the change in 24-h urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that, in hypertensives, the mean effect was -5.39 mmHg (95% CI: -6.62 to -4.15, I (2)=61%) for systolic and -2.82 mmHg (95% CI: -3.54 to -2.11, I (2)=52%) for diastolic BP. In normotensives, the mean effect was -2.42 mmHg (95% CI: -3.56 to -1.29, I (2)=66%) for systolic and -1.00 mmHg (95% CI: -1.85 to -0.15, I (2)=66%) for diastolic BP. Further subgroup analysis showed that the decrease in systolic BP was significant in both whites and blacks, men and women. Meta-analysis of hormone and lipid data showed that the mean effect was 0.26 ng/ml/hr (95% CI: 0.17 to 0.36, I (2)=70%) for plasma renin activity, 73.20 pmol/l (95% CI: 44.92 to 101.48, I (2)=62%) for aldosterone, 31.67 pg/ml (95% CI: 6.57 to 56.77, I (2)=5%) for noradrenaline, 6.70 pg/ml (95% CI: -0.25 to 13.64, I (2)=12%) for adrenaline, 0.05 mmol/l (95% CI: -0.02 to 0.11, I (2)=0%) for cholesterol, 0.05 mmol/l (95% CI: -0.01 to 0.12, I (2)=0%) for LDL, -0.02 mmol/l (95% CI: -0.06 to 0.01, I (2)=16%) for HDL, and 0.04 mmol/l (95% CI: -0.02 to 0.09, I (2)=0%) for triglycerides.

CONCLUSIONS

A modest reduction in salt intake for 4 or more weeks causes significant and, from a population viewpoint, important falls in BP in both hypertensive and normotensive individuals, irrespective of sex and ethnic group. With salt reduction, there is a small physiological increase in plasma renin activity, aldosterone and noradrenaline. There is no significant change in lipid levels. These results provide further strong support for a reduction in population salt intake. This will likely lower population BP and, thereby, reduce cardiovascular disease. Additionally, our analysis demonstrates a significant association between the reduction in 24-h urinary sodium and the fall in systolic BP, indicating the greater the reduction in salt intake, the greater the fall in systolic BP. The current recommendations to reduce salt intake from 9-12 to 5-6 g/d will have a major effect on BP, but are not ideal. A further reduction to 3 g/d will have a greater effect and should become the long term target for population salt intake.

1. The intravenous infusion of I.C.I. 50172 in doses up to 20 mg reduced, although not significantly, the increase in heart rate produced by the infusion of isoprenaline in healthy volunteers; the response to adrenaline was significantly reduced. The infusion of 1 mg propranolol abolished these responses2. After the pre-treatment of subjects with atropine or hexamethonium, I.C.I. 50172 produced a significant reduction in an isoprenaline tachycardia. This reduction was not competitive and did not exceed 50%.3. The intravenous injection of 4 mg I.C.I. 50172 reduced an exercise tachycardia; its effect was less than that of 4 mg propranolol. This difference became greater as the doses of the two drugs were increased. The dextro isomer of propranolol had no effect on the exercise tachycardia; I.C.I. 45763 reduced it to the same extent as propranolol.4. The intravenous injection of I.C.I. 50172 reduced the increase in heart rate produced by tilting a normal subject from the supine to 80 degrees head-up position. After the administration of atropine, I.C.I. 50172 almost abolished the response. In the presence of atropine, I.C.I. 50172 was as active as propranolol in reducing the increase in heart rate on tilting.5. The reason for the differences in the effects of I.C.I. 50172 on the increases in heart rate brought about by the three procedures is not clear.6. The increase in forearm blood flow produced by the infusion of isoprenaline into the brachial artery was not reduced by the intra-arterial administration of I.C.I. 50172.

We previously reported that forest bathing trips enhanced human NK activity, number of NK cells, and intracellular anti-cancer proteins in lymphocytes, and that the increased NK activity lasted for more than 7 days after the trip in male subjects. In the present study, we investigated the effect of forest bathing trip on human NK activity in female subjects. Thirteen healthy nurses, age 25-43 years, professional career 4-18 years, were selected with informed consent. The subjects experienced a three-day/two-night trip to forest fields. On day 1, the subjects walked for two hours in the afternoon in a forest field; on day 2, they walked for two hours each in the morning and afternoon in two different forest fields; and on day 3, the subjects finished the trip and returned to Tokyo after drawing blood and completing a questionnaire. Blood and urine were sampled on the second and third days during the trip, and on days 7 and 30 after the trip. NK activity, numbers of NK and T cells, and granulysin, perforin, and granzymes A/B-expressing lymphocytes in the blood samples, the concentrations of estradiol and progesterone in serum, and the concentrations of adrenaline and noradrenaline in urine were measured. Similar control measurements were made before the trip on a normal working day. The concentrations of phytoncides in the forests were measured. The forest bathing trip significantly increased NK activity and the numbers of NK, perforin, granulysin, and granzymes A/B-expressing cells and significantly decreased the percentage of T cells, and the concentrations of adrenaline and noradrenaline in urine. The increased NK activity lasted for more than 7 days after the trip. Phytoncides, such as alpha-pinene and beta-pinene were detected in forest air. These findings indicate that a forest bathing trip also increased NK activity, number of NK cells, and levels of intracellular anti-cancer proteins in female subjects, and that this effect lasted at least 7 days after the trip. Phytoncides released from trees and decreased stress hormone levels may partially contribute to the increased NK activity.

Anterograde, retrograde, and combined axonal transport methods were used to describe the descending efferent projections of a region of rostral ventrolateral medullary reticular formation important in cardiovascular control. We have termed this region, which contains C1 adrenaline-synthesizing neurons, the nucleus reticularis rostroventrolateralis (RVL). Efferent projections from the RVL innervate all segmental levels of the thoracic intermediolateral and intermediomedial columns as shown using retrograde transport of lectin-conjugated horseradish peroxidase (HRP) or fast blue dye, and anterograde transport of either HRP or labeled amino acids. The projection is highly specific in that there are no projections to thoracic dorsal or ventral horns. This innervation corresponds to the distribution of preganglionic sympathetic neurons in the intermediolateral column. In particular, terminals surround neurons projecting to the adrenal medulla, as demonstrated by combined anterograde and retrograde transport methods at the light level. Terminals containing phenylethanolamine-N-methyl transferase (PNMT) were mapped using immunocytochemical techniques. PNMT-labeled terminals were present at all levels of thoracic intermediolateral column, in a distribution similar to that of the descending projections from the RVL. We have previously shown using double label techniques (Ross et al., '81-'83), that many of the spinal projections of the RVL originate from C1 neurons. These data support our suggestion that certain bulbospinal neurons within the RVL, in particular the C1 neurons, are crucial for tonic vasomotor control.

An imbalance between the overall strain experienced during exercise training and the athlete's tolerance of such effort may induce overreaching or overtraining syndrome. Overtraining syndrome is characterised by diminished sport-specific physical performance, accelerated fatiguability and subjective symptoms of stress. Overtraining is feared by athletes yet there is a lack of objective parameters suitable for its diagnosis and prevention. In addition to the determination of substrates (e.g. lactate, ammonia and urea) and enzymes (e.g. creatine kinase), the possibilities for monitoring of training by measuring hormonal levels in blood are currently being investigated. Endogenous hormones are essential for physiological reactions and adaptations during physical work and influence the recovery phase after exercise by modulating anabolic and catabolic processes. Testosterone and cortisol are playing a significant role in metabolism of protein as well as carbohydrate metabolism. Both are competitive agonists at the receptor level of muscular cells. The testosterone/cortisol ratio is used as an indication of the anabolic/catabolic balance. This ratio decreases in relation to the intensity and duration of physical exercise, as well as during periods of intense training or repetitive competition, and can be reversed by regenerative measures. Correlations have been noted with the training-induced changes of strength. However, it seems more likely that the testosterone/cortisol ratio indicates the actual physiological strain in training, rather than overtraining syndrome. The sympatho-adrenergic system might be involved in the pathogenesis of overtraining. Overtraining appears as a disturbed autonomic regulation, which in its parasympathicotonic form shows a diminished maximal secretion of catecholamines, combined with an impaired full mobilisation of anaerobic lactic reserves. This is supposed to lead to decreased maximal blood lactate levels and maximal performance. Free plasma adrenaline (epinephrine) and noradrenaline (norepinephrine) may provide additional information for the monitoring of endurance training. While prolonged aerobic exercise conducted at intensities below the individual anaerobic threshold lead to a moderate rise of sympathetic activity, workloads exceeding this threshold are characterised by a disproportionate increase in the levels of catecholamines. In addition, psychological stress during competitive events is characterised by a higher catecholamines to lactate ratio in comparison with training exercise sessions. Thus, the frequency of training sessions with higher anaerobic lactic demands or of competition, should be carefully limited in order to prevent overtraining syndrome. In the state of overtraining syndrome and overreaching, respectively, an intraindividually decreased maximum rise of pituitary hormones (corticotrophin, growth hormone), cortisol and insulin has been found after a standardised exhaustive exercise test performed with an intensity of 10% above the individual anaerobic threshold.(ABSTRACT TRUNCATED AT 400 WORDS)

The aim of this study was to test whether environmental enrichment alters the status and responsiveness of pituitary-adrenocortical and sympathetic-adrenomedullary hormones in rats. Previous studies have shown that rats kept in an enriched environment differ from those kept in standard cages in dendritic branching, synaptogenesis, memory function, emotionality and behaviour. In male Wistar rats kept in an enriched environment for 40 days, we studied basal concentrations of hormones, endocrine responses to 5-HT(1A) challenge and responsiveness and adaptation to repeated handling. Environmental enrichment consisted of large plexiglass cages with 10 rats per cage, which contained variety of objects exchanged three times a week. Rats kept in this enriched environment had higher resting plasma concentrations of corticosterone, larger adrenals and increased corticosterone release to buspirone challenge compared to controls. Lower adrenocorticotropic hormone, corticosterone and adrenaline responses to handling were noticed in rats kept in an enriched environment. Exposure to repeated handling led to a more rapid extinction of corticosterone responses in rats kept in an enriched environment. Thus, environmental enrichment leads to pronounced changes in neuroendocrine regulation, including larger adrenals and increased adrenocortical function, which are so far considered to be indication of chronic stress.

1. 45-Ca efflux and resting tension were measured in isolated guinea-pig auricles under conditions known to change the intracellular free Ca ion concentration. 2. In the presence of [Na]o, caffeine (2mM) increases 45-Ca efflux, but does not produce a contracture, while in the absence of [Na]o and [Ca]o caffeine causes a contracture without increasing 45-Ca efflux. Adrenaline (10-minus5-10-minus 4M) with or without theophylline (0-5-1-0mM) has no effect on either 45-Ca efflux or resting tension. 3. In the presence of caffeine the rate of net efflux of Ca depends on [Na]o-2. Caffeine contractures of muscles in Na-free solution relax upon the addition of [Na]o. Relaxation is correlated with the increase in net efflux of Ca. 4. Cyanide (2mM) produces a variable increase in 45-Ca efflux without a concomitant contracture in Na-containing solutions, but in Na, Ca-free solutions a large contracture occurs without significant increase in 45-Ca efflux. 5. A large increase in 45-Ca efflux and a contracture were observed with the 'Ca-ionophore' X 537 A. 6. Changes in membrane potential (K-depolarization) in hypertonic solutions have no significant effect on Na-dependent 45-Ca efflux, which is an agreement with an electroneutral 2:1 Na-Ca exchange. 7. Cyanide and X 537 A both cause a considerable release of Ca ions from isolated guinea-pig heart mitochondria, while caffeine has no effect. 8. The results suggest a powerful role of the Na-Ca exchange system in reducing the intracellular Ca concentration after Ca release from intracellular stores.

Single Purkinje cells from dog, sheep and cow hearts were isolated by injecting a Ca-free collagenase containing Tyrode solution in the space between the connective tissue sheath and the Purkinje cells. A small proportion of these cells survived the isolation procedure and these cells were used for further investigation. The cells showed electrophysiological properties similar to intact Purkinje fibres as indicated by the following results. Maximum diastolic potentials between -70 and -85 mV and specific membrane resistances of 21-32 k omega cm2 indicated that the single cells were not leaky or hyperpermeable . The action potential showed a rapid upstroke, with a maximum rate of rise, Vmax' between 150 and 750 V/s, and two phases of fast repolarization separated by a plateau phase with a duration of about 200 ms. Each action potential was followed by a spontaneous depolarization with an amplitude between 1 and 10 mV. The upstroke of the action potential could be blocked by tetrodotoxin (TTX) in a dose-dependent manner. The rate of depolarization of the action potential was sensitive to changes in membrane potential; the resulting S-shaped curve showed a half-maximum potential of -65 mV and a steepness of 0.46 mV-1. The duration of the action potential was sensitive to external K concentrations, catecholamines and TTX in a way similar to intact Purkinje fibres. Both application of catecholamines and lowering the external K concentration induced spontaneous activity. The cells were used to study the ionic nature of the pace-maker current under voltage-clamp conditions using the two-micro-electrode technique. This pace-maker current was blocked in a voltage-dependent manner by 1 mM-Cs, and was not affected by 1 mM-Ba. The steady-state activation curve was shifted in the depolarizing direction by application of adrenaline. In contrast to voltage-clamp data obtained on the pace-maker current of intact Purkinje fibres, the pace-maker current in a single cell did not reverse near the presumed equilibrium potential for K ions; no reversal could be seen in the voltage range negative to -50 mV. These observations together with preliminary results on the Na and K dependence of the pace-maker current are strong arguments in favour of the hypothesis that the pace-maker current in cardiac Purkinje fibres is an inward current carried by Na and K ions and activates upon hyperpolarization.

1. A phosphohydrolase specific for 5'-nucleotides was characterized by using a particulate fraction from isolated fat-cells. 2. The activity of intact cells towards 5'-AMP was studied. 3. The activity in either situation had the same KM for AMP (45 muM) and was inhibited by low concentrations of ATP (less than 50 muM), but less potently by the ATP analogues AMP-P(CH2)P(adenylyl (beta gamma-methylene)diphosphonate) and AMP-P)NH)P (adenylylimidodiphosphate). 4. Homogenization of intact fat-cells caused no increase in activity and at least 85% of the activity was recovered in the particulate preparation. 5. The preparation of fat-cells used in this work was not freely permeable to AMP. 6. The ability of intact fat-cells to hydrolyse AMP implies that 5'-nucleotidase is an ectoenzyme in fat-cells. 7. Concentrations of ATP 100 times lower than intracellular concentrations inhibit the enzyme when added extracellularly to intact fat-cells, implying that this effect is also medicated at the extracellular face of the membrane. 8. Antibodies raised to whole liver cells and whole fat-cells inhibit 5'-nucleotidase in intact cells. 9. Incubation of intact fat-cells with adrenaline (1 mug/ml) or insulin (50 mui.u./ml) failed to alter the KM or Vmax. of the enzyme.

1. Adrenaline at concentrations too low to cause aggregation of human platelets potentiates the aggregation by adenosine diphosphate. Noradrenaline has the same effect but is less active than adrenaline; isopropylnoradrenaline is inactive or inhibitory.2. The potentiation of adenosine diphosphate by catecholamines is blocked by the adrenergic alpha-receptor antagonists phentolamine and dihydroergotamine but not by 2-halogenoethylamines or by adrenergic beta-receptor antagonists.3. Both the first and second phases of adenosine diphosphate aggregation are potentiated by catecholamines but the second phase more than the first.4. The release from the platelets of adenine nucleotides which is associated with the second phase of aggregation is also increased by adrenaline.

1. The catecholamines adrenaline (A), noradrenaline (NA) and dopamine (DA) were determined in plasma samples of man and various animal species using a highly sensitive radioenzymatic method.2. Basal values were determined under conditions producing virtually no physical or psychic stress in blood obtained through acutely inserted venous catheters in human volunteers, rabbits and cows, through chronic indwelling catheters in cats and rats, and by cubital venipuncture in trained dogs.3. Basal values (pg/ml.) for A, NA, and DA were respectively 64, 203 and 98 in man, 73, 609 and 276 in cats, 166, 392 and 216 in rabbits, 56, 152 and 91 in cows, 204, 376 and 173 in dogs, and 175, 509, and 84 in SPF rats. The NA concentrations were always higher than those of A and DA.4. Gentle handling of rats for 30 sec greatly increased the levels of all catecholamines, especially of A. Even more marked rises were observed during and up to 5 min after restraint stress.5. Blood from the trunk of decapitated rats contained about 20 times more A and 3-4 times more DA and NA than venous blood from catheters in the absence of handling.6. Basal values of plasma catecholamines in small animals can only be obtained through indwelling catheters and in the absence of handling. Most of the previously reported values are too high and are experimental artifacts.

A prospective randomised trial was performed to assess the efficacy of endoscopic injection of adrenaline for actively bleeding ulcers. Emergency endoscopy in 961 patients admitted for upper gastrointestinal haemorrhage identified 68 patients with actively bleeding ulcers. These 68 patients were randomised to receive either endoscopic injection of adrenaline or no endoscopic treatment. After endoscopy both groups were managed in an identical manner, and strict criteria for emergency operation were adhered to in both groups. Bleeding was initially controlled in all 34 patients assigned to the treatment group. Significantly fewer patients in the treatment group than in the control group needed emergency operations (five v 14, respectively). In addition, in the treatment group the median transfusion requirement was significantly less (three v five units of blood) and the median hospital stay shorter (six v eight days). No complications were observed with the injection of adrenaline, and the rate of healing of ulcers in those attending for endoscopy six weeks after discharge was similar in both groups (81% (17 out of 21 patients) in the treatment group v 79% (11 out of 14) in the control group). Injection of adrenaline is effective in stopping bleeding from actively bleeding ulcers.

1. Mesenteric arteries immersed in a depolarizing solution contract in the presence of calcium. These contractions are proportional to the calcium concentration and are reversible.2. Mesenteric arteries immersed in a calcium-free depolarizing solution contract in the presence of adrenaline. Under the experimental conditions reported here, this response develops only about one-third of the contractile tension developed in polarizing solution (modified Krebs bicarbonate).3. Cinnarizine and chlorpromazine inhibit the contractile response to calcium and induce relaxation of depolarized muscle previously contracted by calcium; cinnarizine was 4 times more potent than chlorpromazine in such activity.4. Chlorpromazine inhibits the response to adrenaline in both polarizing and calcium-free depolarizing solutions, whereas cinnarizine inhibits the response in polarizing solution but not that in calcium-free depolarizing solution.5. The significance of these results is discussed.

1. The thromboxane A2 (TP)-receptor blocking activity and specificity of action of GR32191 ([1R-[1 alpha(Z),2 beta,3 beta,5 alpha]]-(+)-7-[5-([1,1'-biphenyl] -4-ylmethoxy)-3-hydroxy-2-(1-piperidinyl)cyclopentyl]-4-heptoni c acid has been evaluated in human platelets and various smooth muscle preparations, both vascular and non-vascular, from a range of species including man. 2. Utilising a platelet counting method to assess aggregation the drug was found to antagonise, in a surmountable manner, human platelet aggregation produced by the TP-receptor agonists, U-46619, EP171 and SQ26655, in whole blood and physiological buffer, with pA2 values of approximately 8.3 and 8.7 in the two media respectively. In the presence of GR32191 the rate of aggregation induced by U-46619 was slowed. 3. The effect of GR32191 upon U-46619-induced platelet shape change and aggregation in platelet-rich plasma was evaluated utilising a turbidometric technique. Both shape change and aggregation were antagonised by GR32191. At relatively high concentrations of the drug a slowing of aggregation and shape change to U-44619 was seen and an unsurmountable antagonism became apparent. 4. The action of GR32191 upon human platelets was specific with platelet aggregation induced by adenosine 5'-diphosphate, platelet activating factor, vasopressin and adrenaline and the inhibitory effects of prostacylin (PGI2), prostaglandin D2 (PGD2) and N-ethylcarboxamide-adenosine (NECA) being unaffected by concentrations of the drug as high as 10 microM. Furthermore, at concentrations of up to 100 microM, the drug itself produced no shape change or aggregation, of human platelets. 5. GR32191 also specifically and potently antagonised in a competitive, surmountable manner the contractile actions of U-46619 upon human vascular smooth muscle and antagonised U-46619-induced contractions of vascular and airways smooth muscle preparations from rat, dog, guinea-pig and rabbit with varying potency. This is discussed in terms of possible heterogeneity of TP-receptors. 6. GR32191 therefore represents a highly potent and specific TP-receptor blocking drug. This profile of action, coupled to its long duration of effect in man described elsewhere, make it an ideal drug tool for elucidating the physiological and pathophysiological role of thromboxane A2.

Prostaglandins stimulate cAMP increase in several biological systems including CNS. The possible participation of a cAMP/Ca2+ related mechanism in prostaglandin induced hyperalgesia in the rat paw, as measured by a modification of the Randall-Selitto method was investigated. A serie of agents was administered in the paw in an attempt to change either Ca2+ or cyclic AMP concentration at the nociceptive terminations. PGE2, dibutyryl cyclic AMP, isoprenaline, noradrenaline, adrenaline, Ca2+ionophore (A23187), BaCl2 caused a dose dependent hyperalgesia. The hyperalgesic effect of these substances was enhanced by methyl-xanthines. Cyclic GMP as well as agents which interfere with Ca2+ influx (verapamil and lanthanum) were local analgesics in normal and hyperalgesic paws.

In a randomised controlled trial, preterm babies undergoing ligation of a patent ductus arteriosus were given nitrous oxide and d-tubocurarine, with (n = 8) or without (n = 8) the addition of fentanyl (10 micrograms/kg intravenously) to the anaesthetic regimen. Major hormonal responses to surgery, as indicated by changes in plasma adrenaline, noradrenaline, glucagon, aldosterone, corticosterone, 11-deoxycorticosterone, and 11-deoxycortisol levels, in the insulin/glucagon, molar ratio, and in blood glucose, lactate, and pyruvate concentrations were significantly greater in the non-fentanyl than in the fentanyl group. The urinary 3-methylhistidine/creatinine ratios were significantly greater in the non-fentanyl group on the second and third postoperative days. Compared with the fentanyl group, the non-fentanyl group had circulatory and metabolic complications postoperatively. The findings indicate that preterm babies mount a substantial stress response to surgery under anaesthesia with nitrous oxide and curare and that prevention of this response by fentanyl anaesthesia may be associated with an improved postoperative outcome.