The vasoactive peptide endothelin is an effective regulator of blood pressure and vascular homeostasis. In addition, the dysregulation of the endothelin signaling pathway is discussed to contribute to ocular diseases like glaucoma or diabetic retinopathy. Furthermore, our workgroup and others showed a protective effect of endothelin 2 for the survival of photoreceptors. In this study, we analyzed mRNA expression levels of the endothelin signaling family in wild-type mice after a puncture of the eye, intravitreal PBS injections, or light-induced photoreceptor degeneration. We observed elevated endothelin receptor a (Eta), endothelin receptor b (Etb), endothelin 1(Et1), and endothelin 2 (Et2) levels, while endothelin 3 (Et3) mRNA levels were not significantly altered. Our findings indicate an important role of the endothelin signaling pathway in response to ocular trauma or disease. These findings make endothelin signaling a promising target to attenuate retinal degeneration.

Alzheimer disease (AD) and stroke coexist and interact; yet how they interact is not sufficiently understood. Both AD and basal ganglia stroke can impair behavioural flexibility, which can be reliably modeled in rats using an established operant based set-shifting test. Transgenic Fischer 344-APP21 rats (TgF344) overexpress pathogenic human amyloid precursor protein (hAPP) but do not spontaneously develop overt pathology, hence TgF344 rats can be used to model the effect of vascular injury in the prodromal stages of Alzheimer disease. We demonstrate that the injection of endothelin-1 (ET1) into the dorsal striatum of TgF344 rats (Tg-ET1) produced an exacerbation of behavioural inflexibility with a behavioural phenotype that was distinct from saline-injected wildtype & TgF344 rats as well as ET1-injected wildtype rats (Wt-ET1). In addition to profiling the types of errors made, interpolative modeling using logistic exposure-response regression provided an informative analysis of the timing and efficiency of behavioural flexibility. During set-shifting, Tg-ET1 committed fewer perseverative errors than Wt-ET1. However, Tg-ET1 committed significantly more regressive errors and had a less efficient strategy change than all other groups. Thus, behavioural flexibility was more vulnerable to striatal ischemic injury in TgF344 rats.

OBJECTIVE

To examine the effect of sildenafil on level of antiangiogenic proteins of preeclampsia. Firstly to examine the effect of sildenafil on serum biomarkers in a patient with preterm preeclampsia. Secondly, to examine the effect of sildenafil on sFlt-1 and soluble endoglin secretion from primary trophoblasts and placental explants.

METHODS

The clinical team administered 50 mg tds sildenafil to a 26-year-old primigravid woman with severe preeclampsia at the threshold of viability (24 3/7 weeks gestation) and we collected bloods to examine the effect of slidenafil on antiangiogenic factors sFlt-1 and soluble endoglin (sENG), pro-angiogenic factor PlGF and vascular cell adhesion molecule 1 (VCAM-1) and endothelin-1 (ET1). We administered sildenafil to human primary trophoblasts and placental explants and explored its effect on sFlt-1 and sENG secretion.

METHODS

We examined serum anti-angiogenic factors sFlt-1 and sENG, pro-angiogenic factor PlGF, the potent vasoconstrictor ET1 and VCAM-1 by ELISA. We explored the effect of sildenafil on sFlt-1 secretion from primary trophoblasts and sFlt-1 and sENG secretion from placental explants.

RESULTS

We found a reduction in serum sFlt-1, stabilisation in sENG and PlGF in a patient with peri-viable preterm preeclampsia administered oral sildenafil 50 mg three times daily (tds). Furthermore there was an initial stabilisation in serum VCAM-1 and a decline in ET1 with sildenafil administration. This was concordant with stabilisation of clinical and biochemical features of preeclampsia. Interestingly, treating placental cells and tissues in vitro with sildenafil did not appear to change sFlt-1 or sENG secretion.

CONCLUSIONS

Sildenafil administration was associated with a reduction in serum sFlt-1 and sENG secretion and increase in PlGF secretion in a patient with preterm preeclampsia, potentially via increasing placental perfusion rather than acting directly on the placenta.

Blood-brain barrier (BBB) breakdown, inflammatory and immune cell activation, and chronic cerebral hypoperfusion are features of multiple sclerosis (MS). The aim is to determine the influence of endothelin-1 (ET1) and asymmetric dimethylarginine (ADMA) on cerebral circulation time (CCT) in patients with MS. In all, 64 patients with MS (39 relapsing-remitting [RR]-MS; 25 secondary progressive [SP]-MS subtype) and 37 controls (C) were studied. Cerebral circulation time was obtained by angiography. Plasmatic ET1 and ADMA were measured by enzyme-linked immunosorbent assay. Lesion load (LL) and brain volume (BV) were obtained by magnetic resonance imaging. Cerebral circulation time was correlated to ET1, ADMA, LL, BV, disease duration (DD), and Expanded Disability Status Scale (EDSS). In MS, both ET1 and ADMA were significantly higher than C (P < .0001); CCT was approximately 2 times lower than C (P < .0001) and significantly slower in SP than in RR-MS (P = .0215). Cerebral circulation time significantly correlated with ET1 in SP-MS (r = 0.38), whereas in RR-MS CCT significantly correlated with DD (r = 0.75). The LL, BV, and EDSS did not correlate with CCT. Endothelin-1 significantly influences CCT delay in SP-MS. Diversely, CCT in RR-MS is independent of ET1 and correlates significantly with DD. We conclude that in RR-MS, DD responds to neurovascular damage accumulation. It is supposed that high ET1 and ADMA levels stem from a protective response to early insults, aimed at opposing nitric oxide overproduction, whereas persistent pathological ET1 and ADMA levels translate into detrimental long-term effects, due to increased brain micro-vessel resistance.

BACKGROUND

Primary myelofibrosis is one of the chronic myeloproliferative disorders characterized by bone marrow fibrosis associated with extramedullary hematopoiesis and osteosclerosis. Endothelin-1 (ET1) is a potent vasoconstrictor that is also a key mediator of osteoblastic bone metastases by stimulating osteoblast proliferation and new bone formation.

METHODS

We report laboratory, radiographic, bone densitometry, and bone histology data of a patient presenting with newly diagnosed, biopsy-proven myelofibrosis and osteosclerosis. We were able to demonstrate abundant ET1 signaling in the bones of our patient.

CONCLUSIONS

We believe that ET1 is responsible for the osteosclerosis that develops with advanced myelofibrosis and suggest that ET1 signaling may play a role in other osteosclerotic settings as well.

Diabetes mellitus (DM) is a major problem all over the world, affecting more people in recent years. Individuals with diabetes are more prone to disease than non-diabetics, especially vascular complications. The aim of this study was to examine the roles of the endothelin (ET)-1 in brain damage formed in a streptozocin (STZ)-induced diabetes model, and the effect of bosentan, which is the non-specific ET1 receptor blocker in the prevention of the diabetes-induced brain damage. To examine the effects of bosentan (50 mg/kg and 100 mg/kg) in this study, the rats were given the drug for 3 months. The rats were divided into four groups: the sham group (n = 10), the diabetic control group (n = 10), the group of diabetic rats given bosentan 50 mg/kg (n = 10) and the group of diabetic rats given bosentan 100 mg/kg (n = 10). Diabetes was induced in the rats by STZ (60 mg/kg i.p.). On day 91, all rats were killed. Brain tissues of the rats were measured by molecular, biochemical and histopathological methods. Antioxidant levels in the therapy groups were observed as quite near to the values in the healthy group. In this study, while the brain eNOS levels in the diabetic groups decreased, the ET1 and iNOS levels were found to be increased. However, in the diabetes group, hippocampus and cerebellum, pericellular oedema and a number of neuronal cytoretraction were increased in neuropiles, whereas these results were decreased in the therapy group. Based on all of these results, ET1 will not be ignored in diabetes-induced cerebral complications.

Many lines of evidence indicate that adrenomedullin (AM) through its coronary vasodilatory and inotropic effects, exerts a major cardiac protective action. Conversely, endothelins (ETs) exert a cardiac detrimental action, which seems to be mainly mediated by the ETA receptor, whose activation promotes coronary constriction and decreases cardiac blood flow. Hence, we have investigated by immunocytochemistry (ICC) and autoradiography the acute effects of ET-1 on endogenous AM system of adult rat heart. Isolated hearts were perfused for 20 min, according to the Langendorff technique, with 2x10(-9) M ET-1[1-21] or ET-1[1-31], which are mixed ETA/ETB and selective ETA receptor agonists, respectively. ICC demonstrated AM-immunoreactivity (IR) in cardiomyocytes, endocardium and especially in the wall of coronary vessels. Quantitative densitometry showed that ET-1[1-31], but not ET1[1-21], significantly decreased AM-IR in coronary vessels, thereby suggesting that ET-1 elicits AM release in the heart through the activation of ETA receptors. Autoradiography demonstrated [125I]AM-binding sites in cardiomyocytes and especially in the wall of coronary venules, and treatment with both ET-1s did not apparently affect them. This location af AM receptors suggests that AM raises cardiac blood flow by evoking coronary artery dilation indirectly, probably via its stimulating effect on NO production, and by decreasing postcapillary resistance via cardiac vein dilation. Collectively, our findings indicate that important functional interrelationships occur between ET and AM systems in the rat heart, where ETs may at least partly hamper their own ETA receptor-mediated decrease in blood flow by increasing the local release of endogenous AM.

Ureteral obstruction with subsequent hydronephrosis is a common clinical complication. Downregulation of renal sodium transporters in obstructed kidneys could contribute to impaired urinary concentrating capability and salt waste following the release of a ureteral obstruction. The current study was undertaken to investigate the role of mitochondrial complex-1 inhibition in modulating sodium transporters in obstructive kidney disease. Following unilateral ureteral obstruction (UUO) for 7 days, a global reduction of sodium transporters, including NHE3, α-Na-K-ATPase, NCC, NKCC2, p-NKCC2, ENaCα, and ENaCγ, was observed, as determined via qRT-PCR and/or Western blotting. Interestingly, inhibition of mitochondrial complex-1 by rotenone markedly reversed the downregulation of NKCC2, p-NKCC2, and ENaCα. In contrast, other sodium transporters were not affected by rotenone. To study the potential mechanisms involved in mediating the effects of rotenone on sodium transporters, we examined a number of known sodium modulators, including PGE2, ET1, Ang II, natriuretic peptides (ANP, BNP, and CNP), and nitric oxide synthases (iNOS, nNOS, and eNOS). Importantly, among these modulators, only BNP and iNOS were significantly reduced by rotenone treatment. Collectively, these findings demonstrated a substantial role of mitochondrial dysfunction in mediating the downregulation of NKCC2 and ENaCα in obstructive kidney disease, possibly via iNOS-derived nitric oxide and BNP.

<AbstractText>Secondary mitral regurgitation (sMR) drives adverse cardiac remodeling in patients with heart failure with reduced ejection fraction (HFrEF). Progression in severity over time contributes to a transition towards more advanced HF stages. Early identification of patients at risk for sMR progression remains challenging. We therefore sought to assess a broad spectrum of neurohumoral biomarkers in patients with HFrEF to explore their ability to predict progression of sMR.</AbstractText><AbstractText>249 HFrEF patients were enrolled. Biomarkers encompassing key neurohumoral pathways in heart failure were sampled at baseline and sMR progression was assessed over 3 years of follow-up.</AbstractText><AbstractText>Of 191 patients with non-severe sMR at baseline, 18% showed progressive sMR within three years after study enrollment. Progression of sMR was associated with higher levels of MR-proADM (adj.OR 2.25, 95%CI 1.29-3.93; P=0.004), MR-proANP (adj.OR 1.84, 95%CI 1.14-3.00; P=0.012), copeptin (adj.OR 1.66, 95%CI 1.04-2.67; P=0.035) and CT-pro-<em>ET1</em> (adj.OR 1.68, 95%CI 1.06-2.68; P=0.027) but not with NT-proBNP (P=0.54).</AbstractText><AbstractText>Increased plasma levels of neurohumoral cardiac biomarkers are predictors of sMR progression in patients with HFrEF and add easily available incremental prognostic information for risk stratification. Importantly, NT-proBNP was not useful to predict progressive sMR in the present analysis. On the contrary, MR-proANP, primarily produced in the atria, copeptin partly triggered by intra-cardiac and intra-arterial pressures, MR-proADM, a marker of forward failure and peripheral released vasoactive CT-pro<em>ET1</em>, increases based on a progressive loading burden by sMR and may thus serve as better predictors of sMR progression.</AbstractText>

The feasibility of identifying epidemiologic markers based solely on the identification of DNA fragments present in outbreak-associated isolates was investigated using Neisseria meningitidis (Nm) as a model system. The clonal structure of Nm has been well characterized using multilocus electrophoresis. In Canada, electrophoretic types <em>ET1</em>, ET5, ET9 and ET21 are being displaced from the natural population by type <em>ET1</em>5, and the latter type is associated with an increased prevalence of serogroup C meningococcal disease. Difference analysis, which uses subtractive hybridization and polymerase chain reaction (PCR) amplification, was employed to identify amplifiable DNA fragments (amplicons) that differ between the <em>ET1</em>5 and the <em>ET1</em>, ET5, ET9 and ET21 genomes. 14 amplicons were cloned which were further characterized by Southern blot analysis to identify six amplicons that represent fragments either unique to or highly polymorphic in the <em>ET1</em>5 genome. Oligodeoxyribonucleotide primer pairs were designed for each of the six amplicons, and PCR amplification was used to determine their prevalence across a panel of 167 Nm isolates representative of other serogroups and ETs. Among group C isolates only two of the six amplicons, designated as A and G, were effective in discriminating <em>ET1</em>5 from non-<em>ET1</em>5 isolates. Amplicon A detects a deletion in the dhps gene which effectively differentiates sulfonamide-sensitive and -resistant serogroup C isolates. The frequency of amplicon A and G detection in the other serogroups and ETs was too great to facilitate their direct use as diagnostic markers for the differentiation of virulent Nm isolates.

BACKGROUND

Vascular hyporeactivity in severe hemorrhagic shock could induce refractory hypotension and is an important cause of death. The global acute inflammatory response induced in shock triggers the over-expression of reactive oxygen species, NO, ET1 and TNF-α, which play essential roles in the pathology of vascular hyporeactivity. This leads to a hypothesis that inhibition of the complement system, the mediator of the inflammatory cascade, might be a promising therapeutic exploration for vascular hyporeactivity.

METHODS

We use cobra venom factor (CVF) and the soluble form of CR1 (sCR1) which deplete or inhibit complement C3 respectively to examine its role in vascular hyporeactivity in a conscious hemorrhagic shock rat model.

RESULTS

We first confirmed the over-activation of C3 during shock and the down-regulation effects of CVF and sCR1 on C3. Then, both CVF and sCR1 could significantly mitigate the over-expression of serum NO, ET-1, TNF-α and reactive oxygen species. Finally, the vascular reactivity of superior mesenteric arteries (SMA) was examined in vitro, which confirmed the massive reduction of vascular reactivity in shock, which was significantly rescued by both CVF and sCR1.

CONCLUSIONS

Inhibition of C3 might improve the reactivity of SMA to norepinephrine during hemorrhagic shock possibly through the downregulation of NO, ET1, TNF-α and reactive oxygen radicals.

OBJECTIVE

To evaluate changes in indicators of endothelial function and their relationship with morphological forms of disease, stage of pathological process and tumor markers, by analysis the peripheral blood of lung cancer (LC) patients.

METHODS

38 LC patients without metastases (mean age - 57 years) prior chemo- and radiotherapy were included in the study. The duration of the disease manifestation was 18 months. 21% of patients had small cell LC, and the rest - non-small cell LC. The ratio of patients with stages IA, IB, IIA, IIB, IIIA and IIIB LC was 1 : 3 : 3 : 4 : 4 : 4. The enzyme immunoassay, spectrophotometry, and statistical data analysis were used.

RESULTS

Endothelial dysfunction of vessels was characterized by increased blood levels of vascular endothelial growth factor (VEGF), endothelin-1 (ET1), homocysteine (HCys), cyclic guanosine monophosphate (cGMP), P-selectin (PSel) and nitrites (NO2) and simultaneously by decreased values of prostacyclin (PgI2). Those were observed in 100; 90; 76; 71; 50; 53 and 79% of LC cases, respectively. Disturbances of vascular endothelial function were associated with patient's age, disease duration, and morphological form and LC stage. Such changes were observed in women with higher prevalence. The studied indices correlated with tumor markers, namely transforming growth factor beta (TGFβ1), fibronectin and osteopontin.

CONCLUSIONS

Indices of vascular endothelial dysfunction in LC can be of diagnostic and prognostic value.

We developed a unique strategy for fabricating hierarchically structured (nanoparticles-in-beads) Zn2SnO4 beads (ZTO-Bs), which were then used to produce ternary metal oxide-based dye-sensitized solar cells (DSSCs). DSSCs were fabricated using the ZTO-Bs as the photoelectrodes and highly absorbable organic dyes as the sensitizers. The DSSCs based on the ZTO-Bs and the organic dyes (SJ-E1 and SJ-ET1) exhibited the highest performance ever reported for DSSCs with ternary metal oxide-based photoelectrodes. The optimized DSSCs exhibited a power conversion efficiency of 6.3% (V(OC) of 0.71 V, J(SC) of 12.2 mA cm(-2), FF of 0.72), which was much higher than that for DSSCs with conventional ZTO-NPs-based photoelectrodes or those based on the popular ruthenium-based dye, N719. The unique morphology of the ZTO-Bs allowed for improvements in dye absorption, light scattering, electrolyte penetration, and the charge recombination lifetime, while the organic dyes resulted in high molar absorbability.

OBJECTIVE

The purpose of this prospective study was to record endothelin-1 (ET-1) concentrations in the second trimester amniotic fluid and compare these values in women who developed intrauterine growth restriction (IUGR) later in pregnancy with those with uneventful pregnancies.

METHODS

Amniotic fluid was retrieved by amniocentesis from 125 women in the second trimester of pregnancy. The levels of ET1 were measured by a sensitive and specific radioimmunoassay.

RESULTS

From the 125 women included in the study 12 had pregnancies that later developed IUGR and 88 had uneventful pregnancies. The ET1 concentration was significantly higher (P<0.005) in women who later developed IUGR than in normal pregnancy (106 pg/ml versus 64.7 pg/ml).

CONCLUSIONS

The amniotic fluid concentration of ET1 is elevated by the second trimester in women who later develop IUGR.

OBJECTIVE

To detect the levels of miR-499 and relative proteins in hearts of mice after exercise training, and investigate the mechanism of exercise-regulative apoptosis.

METHODS

Male C57BL/6 mice were randomly divided into 3 groups( n = 14): sedentary (SE), exercise training 1 (ET1) and exercise training 2 (ET2) group. SE did not do any exercise. ET1 performed swimming training for 8 weeks. ET2 performed the same work as ET1 until the 5th week. Then, mice trained twice a day until the end of training. TUNEL assay was applied to test myocardial apoptosis, RT-PCR and Western blot were used to detect miR-499 and proteins levels respectively.

RESULTS

Compared with SE, stress in ET1 failed to affect apoptotic index (AI) and miR-499-CaN-Drp-1 pathway (P>> 0.05). In contrast, exercise load in ET2 increased miR-499 level, decreased Drp-1 level and AI with statistical significance respectively (P < 0.05), but neither CaN expression nor CaN activity was changed significantly (P>> 0.05).

CONCLUSIONS

Swimming training can inhibit myocardial apoptosis, and the decrease in Drp-l may be responsible for the reduced myocardial apoptosis. CaN, the upstream protein, does not participate in exercise-regulative apoptosis.

OBJECTIVE

To assess the value of endothelin-1 (ET-1) expression in predicting extracapsular extension (ECE) in clinically localized prostate cancer (PCa).

METHODS

ET-1 expression was determined by immunohistochemistry on archival needle biopsies (NBs) from 94 patients (49 pT2 and 45 pT3a) who underwent radical prostatectomy (RP) for clinical T1-T2 PCa. Each sample was analysed independently by two pathologists blinded to the clinical data.

RESULTS

In univariate analysis, high ET-1 expression in NBs, pre-operative prostate-specific antigen (PSA) level >10 ng/ml, percentage of positive biopsy cores and NB Gleason score ≥7 were significantly associated with ECE as determined on subsequent RP. No significant association was found between clinical stage and ECE. In multivariate analysis, there was a significant association with high ET-1 expression in NBs (p = 0.006), pre-operative PSA level >10 ng/ml (p = 0.049), and NB Gleason score ≥7 (p = 0.002). These three pre-operative factors combined provided the best model for predicting ECE with 93.3% sensitivity, 49% specificity, 62.5% positive predictive value, 88.9% negative predictive value. The combination yielded a higher concordance index (0.760 vs 0.720) and offered a higher log partial likelihood than the same model without ET1 (112.8 vs 105.7, p = 0.01).

CONCLUSIONS

ET-1 expression was strongly associated with ECE and, when combined with pre-operative PSA level and Gleason score, improved the predictive accuracy of pre-operative NBs. Its assessment in patients with localized PCa might be useful when making treatment decisions. Further studies with standardisation of immunohistochemical staining and multi-institutional validation are now needed to establish the appropriate use of ET-1 staining in PCa staging and to evaluate inter-observer reproducibility.

By observing gill blood flow using epi-illuminating microscopy, in parallel with cardiovascular recordings and immunohistochemistry, we have tried to identify the receptor mediating endothelin (ET) type 1 (ET1)-induced pillar cell contraction in the lamellae of the Atlantic cod (Gadus morhua). Intra-arterial injection of the specific ET(B) receptor agonist BQ-3020 induced dose-dependent increases in ventral aortic blood pressure, gill vascular resistance, and pillar cell area (indicating contraction). The specific ET(A) receptor antagonist BQ-610 did not prevent either pillar cell contraction or increased gill vascular resistance induced by ET-1 injection. The cardiovascular responses were corroborated by the detection of ET(B) receptor-like immunoreactivity (IR) associated with pillar cells in the lamellar region and in neuroendocrine cells. ET(B) receptor-like IR was also found lining the muscle layer of lamellar arterioles and filament arteries. In contrast, strong ET(A) receptor-like IR was found on branchial nerves throughout the filaments. In addition, ET-like IR was concentrated in neuroendocrine cells in the filament and lamellae. We also present data suggesting that ET-mediated pillar cell contraction is widespread among teleost fish, including Atlantic cod, rainbow trout (Oncorhynchus mykiss), sculpin (Myoxocephalus scorpius), and mackerel (Scomber scombrus). Taken together, our results suggest that an ET(B)-like receptor mediates pillar cell contraction in fishes, whereas ET(A)-like receptors may serve another function in the gill, inasmuch as ET(A) receptor-like IR is found on branchial nerves.

In anaesthetized animals, systemic injection of ET1 at doses from 3 to 100 ng.kg-1 provoked only a transient hypotensive effect. At 300 ng.kg-1 we observed the classical biphasic effect, consisting of a transient lowering of the arterial pressure followed by a long-lasting hypertensive effect. Direct injection of the peptide into the vertebral artery of anaesthetized animals only affected arterial pressure (AP) when the blood-brain barrier was permeabilised. Under these conditions, a dose-dependent decrease in AP was observed, which was not associated with a significant effect on the heart rate. Micro-injections of the peptide in the medullary nucleus reticularis lateralis area (NRL), a medullary vasopressive centre, at doses of 30 to 60 ng.kg-1 led to a significant reduction in mean arterial pressure (MAP) (17 +/- 4% and 36.5 +/- 6%) respectively without a significant change in heart rate. These effects lasted less than 2 hours. These results suggest a possible role of ET1 as a neuromodulator involved in the central regulation of vasomotor tone, in the NRL region.

We sought to investigate effects of exercise training on apoptosis-related microRNAs (miRs) and their validated targets, discussing molecular mechanism of the exercise-induced benefit in heart. Male C57BL/6 mice were randomly assigned to three groups: sedentary (SE), exercise training 1 (ET1) and exercise training 2 (ET2). ET1 swam for 8 weeks, once a day and 5 days per week with incremental load. ET2 performed the same work as ET1 and switched to twice a day by the end of the 5th week. In ET2, positive cell rate (%) tested by TUNEL assay decreased significantly (p < 0.05), and the load decreased miR-1 level by 29% (p < 0.01), also increased miR-30b and miR-21 levels by 32% (p < 0.01) and 18% (p < 0.05) respectively. In addition, Bcl-2 expression was increased by 98% (p < 0.01). p53, PDCD4 and Drp-1 expressions were decreased by 45% (p < 0.01), 6% (p>> 0.05) and 36% (p < 0.01) respectively, compared with SE. In ET1, only miR-30b level was increased by 22% (p < 0.05) with a 48% decrease in p53 level (p < 0.01). Both swimming groups increased Bcl-2/Bax ratio significantly (p < 0.01). This study indicated that apoptosis-related miRs and their downstream proteins in heart can be influenced by swimming training that may be responsible for the exercise-induced cardioprotection.

Both human endothelin 1 (ET1) and rat endothelin 3 (ET3) produced dose-dependent pressor effects in the pithed rat. The pressor actions of ET3 and arginine vasopressin (AVP) were compared with one another in pithed rats in the presence of the calcium channel activator BAY K 8644 or the calcium channel antagonist nifedipine i.a. and also after pretreatment with pertussis toxin i.v. The diastolic pressure recorded in animals treated with the vehicle was 41 +/- 1 mm Hg, and administration of BAY K 8644 increased the diastolic pressure to 53 +/- 3 mm Hg, whereas nifedipine caused a decrease in diastolic pressure to 33 +/- 2 mm Hg. AVP, ET1 and ET3 dose-dependently increased diastolic blood pressure, with AVP being the most potent and producing the greatest total increase in pressure. ET1 was more potent than ET3; however, the maximal increases produced by the endothelins were identical. The actions of ET3 but not AVP were potentiated in the presence of BAY K 8644. Furthermore, nifedipine significantly impaired responses induced by endothelin but not those produced by AVP. It was observed that animals treated with pertussis toxin 3 days before the conduction of the experiments had a significantly lower diastolic blood pressure as compared with saline-treated animals. Treatment with pertussis toxin caused the dose-diastolic pressure response curve to ET to be displaced to the right, whereas the dose-diastolic pressure response to AVP was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

1. The systemic and renal haemodynamic responses to endothelin-1 (ET1) were evaluated and compared to Angiotensin II (AII) in anaesthetized Dahl salt-sensitive (DS) and salt-resistant (DR) rats on either low (0.1% NaCl in diet) or high (8% NaCl in diet) salt intake. 2. Baseline mean arterial pressure on low salt diet was similar in both strains, while on high salt diet it was 73 +/- 4 mmHg in DR rats and 119 +/- 8 mmHg in DS rats (P less than 0.05). Baseline renal blood flow (RBF) and renal vascular resistance (RVR) were similar in all groups. 3. AII in bolus injection induced a short, dose-dependent increase in blood pressure and renal vascular resistance and a fall in renal blood flow. The maximal pressure increase was significantly greater in DS rats on high salt diet than that in each of the other groups (P less than 0.05). The fall in renal blood flow and the increase in renal vascular resistance were attenuated in both strains on low salt diet. 4. ET1 induced an initial decrease followed by a prolonged increase in blood pressure; both phases were similar in all groups. However, renal vascular reactivity to ET1 was markedly modulated by salt intake. On low salt diet, following a bolus injection of ET1 (1 nmol/kg), RBF decreased by 34% in DR and by 20% in DS rats, while on high salt diet RBF decreased by 76% in DR and by 80% in DS rats (P less than 0.05 high vs low salt).(ABSTRACT TRUNCATED AT 250 WORDS)

Our objective is to characterize the vasoactive properties of a 10% alphaalpha diaspirin cross-linked human hemoglobin (alphaalphaHb) and to test the hypothesis that sodium nitroprusside (SNP)-induced relaxation is inhibited in the presence of alphaalphaHb. Experiments were performed on aortic rings from 18 Wistar rats; the rings were suspended in aerated Krebs solution. Changes in isometric tension were measured to increasing concentrations of alphaalphaHb (1.8 x 10(-9) to 10(-4) M) on phenylephrine (PE)-induced contraction (3 x 10(-7) M), on acetylcholine (ACh)-induced relaxation (10(-8) to 10(-6) M), on SNP-induced relaxation (10(-9) and 10(-8) M), and on PE-induced contraction with an endothelin-1 (ET1) receptor antagonist, BQ123 (10(-5) M). Control rings received no alphaalphaHb. A concentration-dependent increase of the PE-precontraction (1.3%, 6.8%, 17.4%, and 34%, respectively) as well as the inhibition and reversal of ACh-induced relaxation was observed after alphaalphaHb. The presence of alphaalphaHb decreased the SNP-induced relaxation in the presence or absence of endothelium. The relaxation induced by SNP was reduced with time in the presence, but not in the absence, of alphaalphaHb. In conclusion, although pharmacological modulation of the vasoconstriction is possible with nitric oxide donors, our findings suggest that in the clinical setting, large sustained donor doses may be required.

The circumventricular organs (CVOs) regulate certain vegetative functions. Receptors for bradykinin (BDK) and endothelin (ET) have been found in some CVOs. The subcommissural organ (SCO) is a CVO expressing BDK-B2 receptors and secreting Reissner's fiber (RF) glycoproteins into the cerebrospinal fluid. This investigation was designed to search for ET receptors in the bovine SCO and, if found, to study the functional properties of this ET receptor and the BDK-B2 receptor. Cryostat sections exposed to (125)I ET1 showed dense labeling of secretory SCO cells, whereas the adjacent ciliated ependyma was devoid of radiolabel. The binding of (125)I ET1 was abolished by antagonists of ETA and ETB receptors. The intracellular calcium concentration ([Ca(2+)](i)) was measured in individual SCO cells prior to and after exposure to ET1, BDK, or RF glycoproteins. ET1 (100 nM) or BDK (100 nM) caused an increase in [Ca(2+)](i) in 48% or 53% of the analyzed SCO-cells, respectively. RF glycoproteins had no effect on [Ca(2+)](i) in SCO cells. ET and BDK evoked two types of calcium responses: prolonged and short responses. Prolonged responses included those with a constant slow decline of [Ca(2+)](i), biphasic responses, and responses with a plateau phase at the peak level of [Ca(2+)](i). ET1-treated SCO explants contained a reduced amount of intracytoplasmic AFRU (antiserum to RF glycoproteins)-immunoreactive material compared with sham-treated control explants. Our data suggest that ET1 and BDK regulate [Ca(2+)](i) in bovine SCO cells, and that the changes in [Ca(2+)](i) influence the secretory activity of these cells.

Pulmonary arterial hypertension (PAH) is a progressive and fatal disorder that any valuable advance in the management of diseases has crucial importance. The present study aimed to compare the Endothelin1 (ET1) inhibitor bosentan which is regarded as standard therapy with different dose regimens of palosuran which is urotensin-II (UII) inhibitor and explore the discrepancy for mean pulmonary arterial pressure (mPAP), UII, ET1 levels, and pulmonary vascular pathology. Seventy rats were randomly divided into seven groups of ten animals each: group 1 (control group) received the vehicle subcutaneously, instead of monocrotaline (MCT) and vehicle; group 2 (MCT group) received subcutaneous MCT and vehicle; and group 3 (MCT + palosuran 30 mg) received subcutaneous MCT and palosuran. Other groups consist of group 4 (MCT + palosuran 100 mg), group 5 (MCT + bosentan 30 mg), group 6 (MCT + bosentan 100 mg), and group 7 (combination therapy). Serum ET1, UII, mPAP levels, and pulmonary arteriolar pathology of different diameter vessels of all groups have been measured and recorded. The ET1 and UII levels of untreated rats (group 2) were significantly higher than the other groups (p < 0.05). Moreover, mPAP levels of group 2 were significantly higher than the other groups (p = 0.001). Finally, 50-125-μm diameter of arteriole wall thickness was found to be significantly thicker in monocrotaline group compared to groups 4 and 6 (p < 0.001). Statistical differences of wall thickness/diameter ratios of arteries and arterioles larger than 125 was found to be significant between group 5, group 6, and the control group (p < 0.001). UII inhibitor is at least as effective as standard therapy bosentan. Findings of this study consolidate that palosuran could be a new future promising therapeutic option in PAH.