Interaction of diet and diabetes on cardiovascular function in rats

Abstract

Genetic rodent models of type 2 diabetes are routinely utilized in studies of diabetes-related cardiovascular disease; however, these models frequently exhibit abnormalities that are not consistent with diabetic complications. The aim of this study was to develop a model of type 2 diabetes that exhibits evidence of cardiovascular dysfunction commonly seen in patients with diabetes with minimal nondiabetes-related pathologies. Young male rats received either control (Con), high-fat (HF; 60%), or Western (Wes; 40% fat, 45% carbohydrate) diets for 2 wk after which streptozotocin (2 x 35 mg/kg ip 24 h apart) was administered to induce diabetes (Dia). Blood glucose levels were higher in Con + Dia and Wes + Dia groups compared with the HF + Dia group (25 +/- 1, 25 +/- 2, and 15 +/- 1 mmol/l, respectively; P < 0.05) group. Liver, kidney, and pancreatic dysfunction and cardiomyocyte lipid accumulation were found in all diabetic animals. Despite lower heart rates in Con + Dia and HF + Dia groups, arterial and left ventricular pressures were not different between any of the experimental groups. All three diabetic groups had diastolic dysfunction, but only HF + Dia and Wes + Dia groups exhibited elevated diastolic wall stress, arterial stiffness (augmentation index), and systolic dysfunction (velocity of circumferential shortening, systolic wall stress). Surprisingly, we found that left ventricular dysfunction and arterial stiffness were more pronounced in the HF + Dia than the Con + Dia group and was similar to the Wes + Dia group despite significantly lower levels of hyperglycemia compared with either group. In conclusion, the HF + Dia group exhibited a stable, modest level of hyperglycemia, which was associated with cardiac dysfunction comparable with that seen in moderate to advanced stages of human type 2 diabetes.