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KMID : 0614020060210010037
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Journal of Pharmaceutical Sciences (C.N.U.)
2006 Volume.21 No. 1 p.37 ~ p.44
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Effect of fluid pressure on L-type Ca^(2+) current in rat ventricular myocytes
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Lee Sun-woo
Woo Sun-Hee
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Abstract
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Cardiac chambers serve as mechanosensory systems during the haemodynamic or mechanical disturbances. To examine possible role of fluid pressure (FP) in the regulation of atrial Ca^(2+) signaling we investigated the effect of FP on L-type Ca^(2+) current(I_(Ca)) in rat ventricular myocytes using whole-cell patch-clamp technique. FP(~40 cm H_(2)O) was applied to whole area of single myocytes with electronically controlled micro-jet system. FP suppressed the magnitude of peak I_(Ca) by ?25% at 0 mV without changing voltage dependence of the current-voltage relationship. FP significantly accelerated slow component of inactivation of I_(Ca), but not its fast component. Analysis of steady-state inactivation curve revealed a reduction of the number of Ca^(2+) channels available for activity in the presence of FP. Dialysis of myocytes with high concentration of immobile Ca^(2+) buffer partially attenuated the FP-induced suppression of I_(ca). In addition, the intracellular Ca^(2+) buffering abolished the FP-induced acceleration of slow component of I_(Ca) inactivation. The results indicate that FP reduces Ca^(2+) current, in part, by increasing cytosolic Ca^(2+) concentration.
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KEYWORD
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fluid pressure, L-type Ca^(2+) current(I_(Ca)), ventricular myocytes, whole-cell patch clamp, Ca^(2+) buffer
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