[Cardiac relaxation and distensibility in energy deficit]

Changes in the cardiac pump function, contractility, relaxation and distensibility in progressive metabolic blockade induced with dinitrophenol, were compared in the guinea pig isolated heart. A fall in relaxation and distensibility occurred first and was more obvious than a fall in contractility or the cardiac output. The same relationships were observed in isolated hearts of rats with myocardial phosphocreatine deficiency. The fall in relaxation and distensibility seem to be the necessary sign of acute or chronic myocardial energy deficiency.