The influence of P‐light chain phosphorylation by myosin light chain kinase on the calcium sensitivity of chemically skinned heart fibres

Abstract

Phosphorylation of the P‐light chain of myosin might be involved in the regulation of cardiac contractility. Thus an enhanced phosphorylation level of the P‐light chain catalyzed by Ca²⁺‐calmodulin‐dependent myosin light chain kinase (MLCK) increased significantly the Ca²⁺ sensitivity of chemically skinned ventricular fibre bundles of the pig. This effect was reversible. Whereas force development at submaximal Ca²⁺ concentration (pCa 5.5) increased by ~ 50% in the presence of MLCK, maximum tension achieved at maximum Ca²⁺‐concentration (pCa 4.3) was not affected.