The Role of Creatine Phosphokinase in Supplying Energy for the Calcium Pump System of Heart Sarcoplasmic Reticulum

Abstract

An investigation of isolated and purified heart sarcoplasmic reticulum performed in the current study indicates the presence of significant creatine phosphokinase (CPK) activity in this preparation. The localization of CPK on the membrane of sarcoplasmic reticulum has been revealed also by an electron microscopic histochemical method.

Under the conditions of the Ca²⁺-ATPase reaction in the presence of creatine phosphate, the release of creatine into the reaction medium is observed, the rate of the latter process being dependent on the MgATP concentration in accordance with the kinetic parameters of the Ca²⁺-ATPase reaction. CPK localized on the reticular membrane is able to maintain the high rate of calcium consumption by the sarcoplasmic reticulum vesicles. The results obtained demonstrate the close functional coupling between CPK and Ca²⁺-ATPase in the membrane of sarcoplasmic reticulum and indicate the important functional role of CPK in supplying energy for the Ca²⁺-ATPase reaction and ion transport across the membrane of heart sarcoplasmic reticulum.

Keywords:

• sarcoplasmic reticulum
• calcium transport
• energy supply
• creatine phosphokinase