Effects of palytoxin on the electrical activity of dog and rabbit heart

Summary Reversible effects of palytoxin, extracted from colonies of the soft coralPalythoa caribaeorum, are described. There is a decrease of both membrane resting potential and overshoot during activity. Rise time of the action potential is prolonged, while repolarization is shortened. The electrical events resemble those seen with metabolic poisons.This work was supported by grant 10897 from the National Heart and Lung Institute, Bethesda, Md., and by grant 3.758. 72 from the Swiss National Science Foundation.I wish to thank Dr W. C. De Mello for hospitality in his department, Dr T. Morales for allowing me to use his equipment, Dr. J. Santos Martínez for providing me with hearts of poisoned and unpoisoned dogs, and Drs E. Toro-Goyco and A. M. Preston of the Department of Biochemistry for letting me have a sample of toxin.