토끼 심방근에서 Na-Ca 교환 전류에 대한 Bay K, cAMP, Isoprenaline 효과

• 영문명: Effects of Bay K, cAMP and Isoprenaline on the Na-Ca Exchange Current of Single Rabbit Atrial Cells
• 발행기관: 대한생리학회
• 저자명: 호원경(Ho, Won-Kyung) 엄융의(Earm, Yung-E)
• 간행물 정보: 『대한생리학회지』제24권 제2호, 377~388쪽, 전체 12쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 1990.12.31

영문 초록

Ca movements during the late plateau phase in rabbit atrium implicate Na-Ca exchange. In single atrial cells isolated from the rabbit the properties of the inward current of Na-Ca exchange were investigated using the whole cell voltage clamp technique. The inward currents were recorded during repolarization following brief 2 ms depolarizing pulse to +40 mV from a holding potential of -70 mV. Followings are the results obtained: 1) When stimulated every 30 sec, the inward currents were activated and reached peak values 6 ~ 12 ms after the beginning of depolarizing pulse. The mean current amplitude was 342 pA/cell. 2) The current decayed spontaneously from the peak activation and the timecourse of the relaxation showed two different phases: fast and slow phase. 3) The recovery of the inward current was tested by paired pulse of various interval. The peak current recovered exponentialy with a time course similar to that of Ca current recovery. 4) Relaxation timecourse was also affected by pulse interval and time constant was reduced almost linearly according to the decrease of pulse interval between 30 sec and 1 sec. 5) The peak inward current was increased by long prepulse stimulation, Bay K, isoprenaline or c-AMP. 6) The relaxation time constant of the inward current was prolonged by Bay K or c-AMP, and shortened by isoprenaline. From the above results, it could be concluded that increase of the calcium current potentiates and prolongs intracellular calcium transients, while shortening of the timecourse by isoprenaline or short interval stimulations might be due to the facilitation of Ca uptake by SR.

키워드

Whole cell voltage clamp technique Inward current of Na-Ca exchange Ca transient SR Ca uptake