Characteristic of the vasorlaxant action of the talatisamine alkaloid and its derivatives
The aim of our research is to study the effect relaxant action of diterpenoid alkaloids talatisamine, 14-O-benzoylthalatisamine and 14-O-acetylthalatisamine was studied using isolated rat aortic rings. Alkaloids significantly and dose-dependently inhibited contraction of the aortic rings caused by high KCl content. At the same time, under these conditions, alkaloids significantly reduced Ca2+-induced contraction of the aortic rings. The relaxing effects of alkaloids are significantly suppressed by verapamil, a potent potentiometer-dependent Ca2+ channel blocker. The alkaloids also significantly reduced norepinephrine-induced aortic ring contraction in normal as well as Ca2+ free Krebs solutions. The data obtained indicate that talatisamine, 14-benzoylthalatisamine and 14-O-acetylthalatisamine exhibit a pronounced relaxant effect in almost the same way in the case of contraction induced by a high content of KCl and norepinephrine. The mechanism of the relaxant action of alkaloids is probably complex and may include suppression of Ca2+influx through voltage-dependent and receptor-driven Ca2+ channels, as well as inhibition of Ca2+transport in the sarcoplasmic reticulum.