Effects of Rhythm and Rate Changes on Inotropic Action of Ouabain.

Abstract

The cat papillary muscle preparation was used to study the effects of rhythm and rate changes on the inotropic action of ouabain. Postextrasystolic potentiation decreased during failure, and the decrease was not reversed by ouabain despite the reversal of the failure of the regularly spaced contractions. When half of another group of muscles was stimulated at a rate of 60/minute, and the other half at a rate of 12/minute, it appeared that the latent period of ouabain is related to elapsed time rather than the total number of contractions.