Nonselective cation current in rabbit ventricular myocytes

Currents contributing repolarization in rabbit ventricular myocytes are very complex because the I-IO.S covers almost the whole repolarislion phase of the action potential. The other components of repolarisation currents, such as I-Kr. and I-Ks, are small. In the present work, with whole-cell patch-clamp technique, a clear evidence was provided,for the existence of a hitherto unreported, voltage-dependent. nonselective can. on current (NSCC) in rabbit ventricular myocytes. Na+, K+, and Cs+ can permeate through the nonselective cation channel and the NSCC can be blocked by Gd3+. The channels are sensitive to Ca2+, Mg+-free, and insulin in bathing solution. Activation of NSCC may provide complex effects on action potential configuration depending oil the basal conditions and the experimental situations. Considering the voltage dependence and rapid activation kinetics of this current, we speculate that this current can provide an important influence oil all repolarisation phases of the action potential as well as contribute to the resting membrane potential in rabbit ventricular myocytes. In addition, it is conceivable that, under certain pathophysiological conditions (e.g., ischemia or excessive mechanical stress), the sensitivity of the channels could be altered in such a way . that the conductance opens even in the presence of physiological Ca2+, Mg2+, and insulin. It might be an important factor on the repolarization of the action potential. Changes in NSCC may lead to an induction or inhibition of arrhythmia. (c) 2005 Prous Science. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000232881700001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Pharmacology & PharmacySCI(E)3ARTICLE6377-3832