The effect of verapamil on the cardiotoxic activity of Portuguese man-o'war (Physalia physalis) and sea nettle (Chrysaora quinquecirrha) venoms.

Verapamil, a calcium antagonist, is effective in delaying death in mice after i.v. challenge with sea nettle (Chrysaora quinquecirrha) or Portuguese man-o'war (Physalia physalis) crude venom. Death caused by these venoms could also be delayed by prior medication of the animals. Continuous EKG monitoring of sea nettle venom-challenged rats demonstrated that a single rapid injection of verapamil might require 4 min to be effective and that up to four repeated injections may be necessary to counteract the venom-induced abnormalities. Verapamil reduced the sea nettle venom-induced positive inotropic effect on isolated guinea pig atrial strips. These data further indicate the effectiveness of verapamil as a therapeutic agent against jellyfish cardiotoxins.