Studies on Cryptolepine

Abstract

Cryptolepine;(1 to 8 µg ml^-1) concentration dependently and competitively (p^A2=6.40 ± 0.03, slope = 1.0) antagonised the vasoconstrictor effect of noradrenaline on the isolated perfused rat mesenteric artery, without producing vasodilatation. Prostaglandin E² (2.5 µg ml^-1) completely reversed cryptolepine block of the response of the artery to noradrenaline during normal Kreb's solution perfusion, but failed to reverse cryptolepine block of the response of the tissue in Ca²⁺ - free Kreb's perfusion medium. Increasing the Ca²⁺ concentration from zero did not restore the reversal of the cryptolepine blockade. It is suggested that Ca²⁺ ions play a significant role in the prostaglandin E₂ induced reversal of cryptolepine block of noradrenaline vasoconstrictor response of the tissue.

Cryptolepine - Prostaglandin E₂ - Ca²⁺ ions - Noradrenaline - Mesenteric artery - Antagonism - Potentiation - Reversal