Cardiac performance and plasma lipids of omega-3 fatty acid-treated streptozocin-induced diabetic rats

We studied the effect of omega-3 fatty acid (omega 3FA) treatment on plasma lipids and cardiomyopathy in the diabetic rat. The omega 3FA preparation used was Promega. Male Wistar rats (250-275 g) were rendered diabetic by streptozocin (STZ; 55 mg.kg-1). Nondiabetic control rats received the vehicle alone. Two weeks after STZ or vehicle injection, control and diabetic rats were randomly assigned to either a treated or untreated group. Promega was administered at a dose of 0.5 ml.kg-1.day-1 by oral gavage for 4 wk, after which the rats were decapitated, plasma collected, and isolated working heart performance studied. Promega treatment did not affect plasma glucose, triglyceride, or cholesterol concentrations of either the control or diabetic rats. Cardiac performance was assessed by measuring the left ventricular response to changing left atrial filling pressures (7.5-20 cm H2O). The treatment had no effect on peak left ventricular developed pressure (LVDP) or maximal rate of change of left ventricular pressure during systole (+dP/dtmax) or diastole (-dP/dtmax) in the nondiabetic control rats. LVDP and +/- dP/dt were significantly improved (P less than .05) in the treated diabetic rats compared with untreated diabetic rats, although cardiac performance did not improve to the nondiabetic level. Cardiac sarcoplasmic reticulum (SR) calcium transport activity was not affected by the treatment in the control rats but was significantly improved (P less than .05) in the treated diabetic rats. These data suggest that omega 3FA treatment partially blocks the development of experimental diabetic cardiomyopathy, possibly by affecting SR calcium transport activity.