IMPROVEMENT IN CARDIAC-FUNCTION IN STREPTOZOTOCIN-DIABETIC RATS BY SALT LOADING

Effects of salt loading by drinking 0.9% NaCl solution on the myocardi al performance in nondiabetic and diabetic Wistar rats were studied us ing the isolated working heart apparatus. Body weight and fluid and fo od intakes of these animals were monitored. Blood pressure and plasma levels of glucose, insulin, cholesterol, and triglycerides were also m easured. Diabetes was induced by intravenous injection of streptozotoc in (60 mg/kg). Diabetic rats were found to develop myocardial dysfunct ion at 8 weeks after STZ injection, accompanied by significant increas es in food and fluid intakes, slowed body weight gain, hyperglycemia, hypoinsulinemia, and hyperlipidemia but without significant changes in blood pressure. Salt loading did not cause significant changes in any of the parameters studied in nondiabetic rats. However, in streptozot ocin-diabetic rats given saline to drink, the impaired myocardial func tion was significantly improved and was associated with a significant reduction in hyperphagia and hyperlipidemia. plasma glucose levels sig nificantly decreased at weeks 1-3 but increased to the levels of untre ated diabetic animals at weeks 4-7. There was an increase in fluid int ake, but neither blood pressure nor plasma insulin levels were signifi cantly affected. It is suggested that the improvements in cardiac func tion and hyperlipidemia in diabetic rats by salt loading may be relate d to each other; however, the mechanisms for these effects are not cle ar but are unlikely to be due to changes in glycemic control.