부자의 강심작용에 대한 약리학적 검토

Abstract

A chloroform insoluble, and n-butanol extractable fraction from Aconiti tuber has been recently known to have cardiostimulatory effect. The Aconiti tuber butanol fraction elicited a potent positive inotropic effect on the isolated cardiac muscle preparations of various animals including rat, rabbit and cat. It increased the rate and the intensity of the developed isometric tension , while shortened the time from onset of contraction to peak tension and the total duration of contraction. In contrast with digitalis cardiac glycoside , it does not show the animal species differenee in the positive inotropic effect, and produces no toxic signs by a 1000 fold concentration of minimal positive inotropic dose. In the afterloaded simultaneous isotonic and isorne tric contraction of cat papillary muscle , Aconiti tuber butanol fraction increased the maximal velocity of shortening and the maximal developed force , however it had no appreciable influence on the properties of the series elastic component of the muscle contractile model. The excitability of the isolated rabbit atrium increased slightly at low concentration(•:;x 1O- ' g/ml) , while decreased at higher concentration, and the refractory period of right atrium was slightly prolonged at 2 x 10-3g/ml. Analyzing the relation of the positive inotropic effect of Aconiti tuber butanol fraction to the frequency of contraction, more powerful inotropic effect was produced at shorter stimulation interval. The cumulated positive inotropic effect of activation (PIEA) and the amount of PIEA produced by each contraction increased significantly with the higher stimulation frequency either In contrast to digitalis cardiac glycoside , Aconiti tuber butanol fraction did not show potassium dcpendency in the positive inotropic effect. It produced almost same increment of isometric tension and elF/ dt at varying concentrations of extracellular patassium. However, the dependency of the inotropic effect of Aconiti tuber on the extracellular calcium has been observed , and a synergistic or additive action could be demonstrated between two substances. Aconiti tuber butanol fraction in concentration of 10-7 -10-2g/ml does not seem to have direct eficct on either the cardiac contractile proteins or ATP ase of actomyosin, but the membrane bound Na-K-ATPase activity was markedly inhibited in the usual inotropic concentrations. In anesthetized rabbit, heart rate and left γentricular pressure were reduced by Aconiti tuber butanol fraction. It caused a slight and variable incrcase in cardiac out-put and carotid blood flow, but systemic arterial pressure decreased in a dose-dependent mannero