Effect of ouabain on hyperthermic contracture of cat papillary muscle

¹ Department of Physiology, State University of New York, Downstate Medical Center, Brooklyn, New York

Isolated cat papillary muscles were used to demonstrate the effects of temperatures up to 48 C on resting length and amplitude of isotonic contraction. Progressive heating caused an initial increase and then a marked decrease in resting length; the shortening was irreversible in most instances. Progressive heating caused a decrease and then an increase in amplitude of contraction. Maintained high temperature caused a subsequent decrease in contraction. The permanence of these changes depended on the maximum temperature reached and the duration of exposure. Ouabain and epinephrine failed to influence the contracture caused by high temperature.