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Guinea pig 단일 심실근 세포의 칼슘전류에 대한 아드레날린성 약물의 효과
백승곤,심태섭,방효원 중앙대학교 의과대학 의과학연구소 1991 中央醫大誌 Vol.16 No.4
In order to investigate the effects of sympathomimetic drugs on the calcium currents, whole cell patch clamp technique was used in ventricular cells of the guinea-pig. Single ventricular cells were isolated by Langedorff perfusion method with collagenase. T-type and L-type Ca-currents were recorded in different holding potentials. T-type Ca-current was activated from more negative membrane potentials(around -50 mV) and was inactivated very rapidly, whereas L-type Ca-current was activated from -30 mV and inactivated with two time constants(fast and slow components). Replacement of calcium with barium increased the activation magnitude of L-type Ca-current and delayed inactivation time course, but did not affect T-type Ca-current significantly. Nifedipine blocked and Bay K 8644 increased L-type Ca-current with voltage-dependent manner. T-type Ca-current, however, was relatively insentive to dihydropyridine compuonds. Isoproterenol which is known to have mainly beta-agonist increased L-and T-type Ca-currents and propranolol reversed the effect of isoproterenol. Phenylephrine(alpha-agonist) and phentolamine(alpha-blocker) have no significant effects on the Ca-currents. From the above results it is suggested that L-type and T-type Ca-currents are present in guineapig ventricular myocytes and very sensitive to beta-agonist or-antagonist, but relatively insensitive to drugs acting on alpha-receptors.