Enhancement of the T-type calcium current by hyposmotic shock in isolated guinea-pig ventricular myocytes.
Published on Jul 1, 2001in Journal of Molecular and Cellular Cardiology5.055
· DOI :10.1006/jmcc.2000.1399
Abstract C. Pascarel, F. Brette and J.-Y. Le Guennec. Enhancement of the T-type Calcium Current by Hyposmotic Shock in Isolated Guinea-pig Ventricular Myocytes. Journal of Molecular and Cellular Cardiology (2001) 33 , 0000–0000. It is known that swelling and shrinkage of cardiac cells can modulate their electrical activity. However, the effects of osmotic manipulation on cardiac T-type calcium current (I CaT ) has not been previously reported. In this study, we have examined the effects of cell swelling on I CaT , using the whole cell patch clamp configuration. Isolated guinea-pig ventricular myocytes were swollen by an external hypotonic challenge (0.7 T). We found that I CaT is enhanced during a hypotonic shock. This current has been determined to be the T type calcium current since it is rapidly activated and inactivated, its threshold was at negative potentials and was blocked by 40 μ m Ni 2+ . Disruption of microfilaments by cytochalasin D and of microtubules by colchicine prevented the activation of I CaT during cell swelling. Taxol had no effect. These results indicate that I CaT is increased during cell swelling and this effect needs an intact cytoskeleton.