백서 심실 근세포 L형 Ca2+ 전류에 대한 유체압력의 효과

Effect of Fluid Pressure on L-type Ca2+ Current in Rat Ventricular Myocytes

Cardiac chambers serve as mechanosensory systems during the heamodynamic or mechanical disturbances. To examine a possible role of fluid pressure (FP) in the regulation of atrial Ca2+signaling we investigated te effect of FP on L-type Ca2+ current (ICa in rat ventricular myocytes with electronically comtrolled micro-jet system. FP suppressed the magnitude of peak ICa by =~ 25% at 0mV without changing voltage dependence of the current-voltage relationship. FP significantly accelerated slow component in inactivation of ICa+but not its fast component. Analysis of steady-state inactivation curve revealed a reduction of the number of Ca2+ channels available for activity in the presence of FP. Dialysis of myocytes with high concentration of immobile Ca2+ buffer partially attenuated the FP-induced suppression of ICa+. In addition, the intracellular Ca2+ buffering abolished the FP-induced acceleeration of slow component in ICa inactivation. These results indicate that FP sup- preses Ca2+ currents, in part, by increasing cytosolic Ca2+ concentration.