Structural and enzymatic properties of cardiac myosin in ischaemic and non-ischaemic regions of the rat myocardium.

In rats with ligation of the left coronary artery changes in ATPase activity and structure of cardiac myosin in both ischaemic and non-ischaemic zones of the myocardium were followed. In control animals, ATPase activity and the structure of the myosin molecule in right and left ventricles did not differ. Non-specific factors, such as anaesthesia and thoracotomy, can result in a decrease or an increase in ATPase activity respectively. One hour after ligation of the left coronary artery ATPase activity increased in the right, non-ischaemic myocardium and there was a significant right-to-left difference. Four hours after ligation, ATPase activity in both ventricles significantly decreased and the right-left difference disappeared. Within 48 h, normal values were found only in the non-ischaemic right ventricle. Ligation of the left coronary artery results after 48 h in the formation of structural alterations in cardiac myosin, primarily in the left, ischaemic myocardium. These changes are characterised by the formation of myosin aggregates, which have a significantly lower ATPase activity in comparison with monomeric myosin.