THE LATENT PERIOD OF RELAXATION DUE TO ANODAL CURRENT PULSE IN OYSTER MYOCARDIUM

Abstract

In oyster myocardium, the latent period of relaxation is much longer than that of contraction, namely the mean value of the former is 311 msec and that of the latter is 88 msec at 15-18°C. This appears to show that the mechanisms of relaxation and of contraction are different from each other. The latent period of relaxation remains within a fairly constant range irrespective of the intensity and the duration of stimulus or muscle tension. Moreover, it does not show any recognizable change in the administration of metabolic inhibitors or narcotics. Only the change in temperature of the external fluid has a remarkable positive effect on the latent period of relaxation. The temperature coefficient (Q₁₀) is about 2. This result suggests that the latent period of relaxation has some relations to chemical processes.