Sensitivity of cultured embryonic heart cells to cardiotoxin obtained from Naja naja siamensis venom.

Clumps of embryonic chick heart cells in culture were exposed to cardiotoxin prepared by Sephadex CM-50 fractionation from snake (Naja naja siamensis) venom. Cardiotoxin irreversibly depolarized these cells. More of the cells cultured from 4-day embryos, than from 12–13-day embryos, continued to beat spontaneously after 30 min exposure to the toxin at a concentration of 15–20 μg per ml.