Action of DOC and Serum on the Frog Heart

Abstract

A method is described for the isometric registration of the perfused frog heart. Methods are given for the study of the staircase phenomenon. The staircase is abolished by low temp. and by a low K-ion concn. Abolition of the staircase is accompanied by a slowed contraction and relaxation. Serum and DOC produce actions similar to low K and temp. No direct interaction could be demonstrated between DOC and contractile proteins. Probably DOC acts on the staircase and on contraction in general by modifying the selective activity of the membrane.