Insulin treatment and myocardial function in isolated, perfused heart from diabetic rat

Difficulty of some patients to maintain adequate cardiac output following the termination of cardiopulmonary bypass remains a significant problem in cardiac surgery. The patients with diabetes mellitus frequently fail to respond to therapy after the cardiopulmonary bypass. However, little is known about the relationship between the control of diabetes mellitus and myocardial performance. The purpose of the present study was to look at the effect of diabetes and insulin treatment upon ventricular function and myocardial microcirculation in isolated perfused rat heart. Experimental diabetes was induced by injecting streptozotocin and some of them were treated by insulin injection. Severe form of ischemia was induced in heart from acute form of diabetes and functional recovery was compared among the control, diabetic and insulin treated groups. In chronic form of diabetes, myocardial function and microcirculation which was measured by local H2 generation method were studied during aerobic perfusion and mild form of ischemic perfusion. The hearts from experimental diabetes were more susceptible to ischemia and insulin pretreatment protected the functional alterations. This beneficial effect of insulin was associated with improved glucose and fatty acid metabolism. Myocardial microcirculation in hearts from diabetes was significantly less than in control, however, this was not correctable by the insulin treatment.