Protective effect of glucose on the anoxic myocardium of old and young mice.

To compare the function of old and young hearts contracting under identical conditions, isolated hearts of young and old C57BL/6J mice were perfused using a Langendorff preparation. During a 3-min period of anoxia some hearts showed a decrease in systolic pressure, while other hearts developed contracture. The incidence and magnitude of contracture was greater in the old hearts and they also showed a significantly larger decline in contractility. Increasing the glucose concentration improved the performance of both age groups but the performance of the old hearts was still inferior to that of the young. The glycogen content and utilization were virtually the same in the two age groups. When iodoacetate was added, all hearts developed contracture and the magnitude of the contracture was greater than in the absence of iodoacetate; during the period of reoxygenation, the young hearts recovered but, the old hearts developed a second contracture. A brief period of anoxia is more debilitating to old C57BL/6J hearts than to young ones.