The coronary vasoconstrictor action of extract IV from the dahlia sea anemone Tealia felina L.

Extract IV, a partially purified preparation of the toxin from the sea anemone Tealia felina, produced marked bradycardia and arrhythmias in the rat in vivo. In the Langendorff rat heart preparation perfused at constant pressure extract IV (0.0224 AU/ml) reduced the force of contraction by 81.3 +/- 7.2%, n = 6, and the coronary flow by 82.0 +/- 4.7%, n = 5. When the preparation was perfused at constant flow rate, extract IV (0.072 AU/ml) increased the coronary circulation resistance from 3.76 +/- 1.09 (control) to 36.94 +/- 12.26 mmHg/ml/min. The force of contraction was also markedly reduced. The extract produced bradycardia in preparations perfused at constant pressure but not in those perfused at constant flow rate. The extract did not affect isolated atria preparations. It was concluded that the bradycardia produced in vivo and in preparations perfused in vitro at constant pressure was probably secondary to the coronary vasospasm produced, which could contribute to the cardiotoxicity of the extract.