Studies on Cryptolepine

Abstract

Cryptolepine;(1 to 8 µg ml -1 ) concentration dependently and competitively (p A 2=6.40 ± 0.03, slope = 1.0) antagonised the vasoconstrictor effect of noradrenaline on the isolated perfused rat mesenteric artery, without producing vasodilatation. Prostaglandin E 2 (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 Ca 2+ - free Kreb's perfusion medium. Increasing the Ca 2+ concentration from zero did not restore the reversal of the cryptolepine blockade. It is suggested that Ca 2+ ions play a significant role in the prostaglandin E 2 induced reversal of cryptolepine block of noradrenaline vasoconstrictor response of the tissue. Key Word Index Cryptolepine - Prostaglandin E 2 - Ca 2+ ions - Noradrenaline - Mesenteric artery - Antagonism - Potentiation - Reversal