Cadmium block of calcium current in frog sympathetic neurons.
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Journal: 1992/December - Biophysical Journal
ISSN: 0006-3495
Abstract:
Cd2+ blocks whole-cell calcium currents in frog sympathetic neurons by 50% at approximately 300 nM. Strong depolarizations rapidly reverse that blockade (tau = 1.3 ms at +120 mV). Reblocking follows bimolecular kinetics (rate = 1.2 x 10(8) M-1 s-1) at voltages where channels are mostly open (0 to +30 mV). The unblocking rate is approximately 50 s-1, so the dissociation constant calculated from the rate constants is approximately 400 nM. Steady-state block is strong at -80 mV, so closed channels can also be blocked. However, reblocking is extremely slow (tau = 1-2 s) at voltages where the channels are mostly closed. The rates for Cd2+ entry and exit are greater than 100-fold lower for closed channels than for open channels, and closed channels appear to be closed at both ends.
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Biophys J 63(1): 162-168
PMID: 1330026

Cadmium block of calcium current in frog sympathetic neurons.

Abstract

Cd2+ blocks whole-cell calcium currents in frog sympathetic neurons by 50% at approximately 300 nM. Strong depolarizations rapidly reverse that blockade (tau = 1.3 ms at +120 mV). Reblocking follows bimolecular kinetics (rate = 1.2 x 10(8) M-1 s-1) at voltages where channels are mostly open (0 to +30 mV). The unblocking rate is approximately 50 s-1, so the dissociation constant calculated from the rate constants is approximately 400 nM. Steady-state block is strong at -80 mV, so closed channels can also be blocked. However, reblocking is extremely slow (tau = 1-2 s) at voltages where the channels are mostly closed. The rates for Cd2+ entry and exit are greater than 100-fold lower for closed channels than for open channels, and closed channels appear to be closed at both ends.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Almers W, McCleskey EW. Non-selective conductance in calcium channels of frog muscle: calcium selectivity in a single-file pore. J Physiol. 1984 Aug;353:585–608.[PMC free article] [PubMed] [Google Scholar]
  • Brown AM, Tsuda Y, Wilson DL. A description of activation and conduction in calcium channels based on tail and turn-on current measurements in the snail. J Physiol. 1983 Nov;344:549–583.[PMC free article] [PubMed] [Google Scholar]
  • Byerly L, Chase PB, Stimers JR. Calcium current activation kinetics in neurones of the snail Lymnaea stagnalis. J Physiol. 1984 Mar;348:187–207.[PMC free article] [PubMed] [Google Scholar]
  • Byerly L, Chase PB, Stimers JR. Permeation and interaction of divalent cations in calcium channels of snail neurons. J Gen Physiol. 1985 Apr;85(4):491–518.[PMC free article] [PubMed] [Google Scholar]
  • Chiu SY. Inactivation of sodium channels: second order kinetics in myelinated nerve. J Physiol. 1977 Dec;273(3):573–596.[PMC free article] [PubMed] [Google Scholar]
  • Chow RH. Cadmium block of squid calcium currents. Macroscopic data and a kinetic model. J Gen Physiol. 1991 Oct;98(4):751–770.[PMC free article] [PubMed] [Google Scholar]
  • Gutnick MJ, Lux HD, Swandulla D, Zucker H. Voltage-dependent and calcium-dependent inactivation of calcium channel current in identified snail neurones. J Physiol. 1989 May;412:197–220.[PMC free article] [PubMed] [Google Scholar]
  • Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. [PubMed] [Google Scholar]
  • Hess P, Tsien RW. Mechanism of ion permeation through calcium channels. Nature. 309(5967):453–456. [PubMed] [Google Scholar]
  • Hirning LD, Fox AP, McCleskey EW, Olivera BM, Thayer SA, Miller RJ, Tsien RW. Dominant role of N-type Ca2+ channels in evoked release of norepinephrine from sympathetic neurons. Science. 1988 Jan 1;239(4835):57–61. [PubMed] [Google Scholar]
  • Jones SW. Time course of receptor-channel coupling in frog sympathetic neurons. Biophys J. 1991 Aug;60(2):502–507.[PMC free article] [PubMed] [Google Scholar]
  • Jones SW, Jacobs LS. Dihydropyridine actions on calcium currents of frog sympathetic neurons. J Neurosci. 1990 Jul;10(7):2261–2267.[PMC free article] [PubMed] [Google Scholar]
  • Jones SW, Marks TN. Calcium currents in bullfrog sympathetic neurons. I. Activation kinetics and pharmacology. J Gen Physiol. 1989 Jul;94(1):151–167.[PMC free article] [PubMed] [Google Scholar]
  • Kuffler SW, Sejnowski TJ. Peptidergic and muscarinic excitation at amphibian sympathetic synapses. J Physiol. 1983 Aug;341:257–278.[PMC free article] [PubMed] [Google Scholar]
  • Lansman JB, Hess P, Tsien RW. Blockade of current through single calcium channels by Cd2+, Mg2+, and Ca2+. Voltage and concentration dependence of calcium entry into the pore. J Gen Physiol. 1986 Sep;88(3):321–347.[PMC free article] [PubMed] [Google Scholar]
  • Plummer MR, Logothetis DE, Hess P. Elementary properties and pharmacological sensitivities of calcium channels in mammalian peripheral neurons. Neuron. 1989 May;2(5):1453–1463. [PubMed] [Google Scholar]
  • Swandulla D, Armstrong CM. Calcium channel block by cadmium in chicken sensory neurons. Proc Natl Acad Sci U S A. 1989 Mar;86(5):1736–1740.[PMC free article] [PubMed] [Google Scholar]
  • Taylor WR. Permeation of barium and cadmium through slowly inactivating calcium channels in cat sensory neurones. J Physiol. 1988 Dec;407:433–452.[PMC free article] [PubMed] [Google Scholar]
  • Yellen G. Single Ca2+-activated nonselective cation channels in neuroblastoma. Nature. 1982 Mar 25;296(5855):357–359. [PubMed] [Google Scholar]
Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106.
Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106.
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Abstract
Cd2+ blocks whole-cell calcium currents in frog sympathetic neurons by 50% at approximately 300 nM. Strong depolarizations rapidly reverse that blockade (tau = 1.3 ms at +120 mV). Reblocking follows bimolecular kinetics (rate = 1.2 x 10(8) M-1 s-1) at voltages where channels are mostly open (0 to +30 mV). The unblocking rate is approximately 50 s-1, so the dissociation constant calculated from the rate constants is approximately 400 nM. Steady-state block is strong at -80 mV, so closed channels can also be blocked. However, reblocking is extremely slow (tau = 1-2 s) at voltages where the channels are mostly closed. The rates for Cd2+ entry and exit are greater than 100-fold lower for closed channels than for open channels, and closed channels appear to be closed at both ends.
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