Effects of smooth muscle relaxant (Aspaminol) on Ca-uptake by mitochondrial and microsomal fractions from rat uterus.

Abstract

A smooth muscle relaxant, Aspaminol (1,1-diphenyl-3-piperidinobutanol hydrochloride) relaxed a KCl-depolarized rat uterus and shifted a dose response curve of CaCl2 towards higher doses. Asparminol, a teritary amine, may penetrate into the KCl-depolarized muscle cells. In order to study mechanisms for relaxation of the KCl-depolarized rat uterus by Aspaminol, effects of Aspaminol on Ca-uptake by mitochondrial and microsomal fractions from the rat uterus were studied. Aspaminol inhibited Ca-uptake by both fractions. Inhibition of Ca-uptake by the mitochondrial fraction seems to increase intracellular Ca2+. Therefore, inhibition of Ca-uptake by the mitochondrial fraction is considered to be not associated with relaxation of uterus induced by Aspaminol. Since the microsomal fraction is known to form microsacs, the microsomal fraction was used as smooth muscle models. Inhibitory effect of Aspaminol on Ca-uptake by the microsomal fraction suggest a decrease in the intracellular concentration of Ca2+ of the uterine smooth muscle relaxed under the influence of Aspaminol.