Voltage dependent physiology

Hancox, J.C., Levi, A.J. and Witchel, H.J. (1998) Time course and voltage dependence of expressed hERG current compared with native rapid delayed rectifier K+ current during the cardiac ventricular action potential. Pflugers Archiv European Journal of Physiology, 436, 843-853. 

Physiologic effect Inhibition of ion conductance Repetitive firing, shift of voltage dependence of activation Inhibition of phosphorylase phosphatases 1 and 2a Receptor-induced depolarization and excitation Unknown Ciguatoxin repetitive firing, shift of voltage dependence of activation Maitotoxin calcium ion influx... 

Ion channels are large proteins which form pores through the neuronal membrane. The precise structure and function of the ion channels depend on their physiological function and distribution along the dendrites and cell body. These include specialized neurotransmitter-sensitive receptor channels. In addition, some ion channels are activated by specific metal ions such as sodium or calcium. The structure of the voltage-dependent sodium channel has been shown to consist of a complex protein with both a hydrophilic and a hydrophobic domain, the former domain occurring within the neuronal membrane while the latter domain occurs both inside and outside the neuronal membrane. 

Hofmann, F., Lacinova, L. and Klugbauer, N. (1999) Voltage-dependent calcium channels from structure to function. Reviews of Physiology, Biochemistry, and Pharmacology 139, 33-87. 

Day, T.A., Kim, E., Bennett, J.F. and Pax, R.A. (1 995) Analysis of the kinetics and voltage-dependency of transient and delayed K+ currents in muscle fibres isolated from the flatworm Schistosoma mansoni. Comparative Biochemistry and Physiology 111, 79-87. 

An increase in the extracellular K+ concentration from 2 to 8 mM (the limits of the physiological range) leads to a 4-5-fold increase in the rate of aldosterone secretion by the adrenal glomerulosa cell [24,25]. This increase in [K+] leads to a depolarization of the plasma membrane of the cell. This depolarization causes the opening of two types of voltage-dependent Ca2+ channel in this membrane, and thus to a 4-fold increase in the rate of Ca2+ influx. The total cell calcium and the [Ca2+]j both... 

Batrachotoxin at present remains an important, indeed often essential, tool for mechanistic studies of the function of voltage-dependent sodium channels and for the investigation of the role of depolarization and/or influx of sodium ions on physiological functions. Batrachotoxin has been particularly useful in the study of the function of sodium channels, purified and reconstituted into artificial lipid bilayers. A summary and overview of the extensive studies with batrachotoxin appeared in 1986 (5). Since that time more than 100 articles dealing with the activity of batrachotoxin and/ or the radioligand batrachotoxinin A 20a-[ H]benzoate have appeared, and it is beyond the scope of the present review to summarize this extensive recent literature. A few selected developments are as follows allosteric enhancement of the action of batrachotoxins by pyrethroid insecticides... 

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