Abnormalities of carbohydrate and lipid metabolism in Dahl rats

Abstract

Plasma glucose, insulin, and triglyceride concentration, blood pressure, and insulin action on isolated adipocytes were determined in weight-matched Sprague-Dawley, Dahl salt-resistant, and Dahl salt-sensitive rats. Blood pressure and plasma glucose concentrations were not significantly different in the three groups. However, Dahl salt-sensitive rats had significantly higher plasma insulin (39±2 microunits/ml) and triglyceride (213±11 mg/dl) concentrations than did Sprague-Dawley rats (27±2 microunits/ml and 101±6 mg/dl, respectively). Values for insulin (34±4 microunits/ml) and triglyceride (159±11 mg/dl) were intermediate in Dahl salt-resistant rats. In contrast, maximal insulin-stimulated glucose transport was significantly lower in adipocytes isolated from Dahl salt-sensitive as compared with Sprague-Dawley rats (400±16 versus 523±14 fl/cell/sec), with Dahl salt-resistant rats again having intermediate values. However, the ability of insulin to maximally inhibit catecholamine-stimulated lipolysis was similar in all three groups, averaging ∼20% of the activity present in the absence of insulin. All of these differences were seen when the rats were eating conventional chow and did not change in Dahl rats after 2 weeks of an 8% NaCl diet. On the other hand, the predicted rise in blood pressure took place in Dahl salt-sensitive rats, increasing from 147±4 to 181±6 mm Hg. These data indicate that Dahl rats have higher values for plasma triglyceride and insulin concentration than control Sprague-Dawley rats, associated with a defect in insulin-stimulated glucose uptake by isolated adipocytes. These metabolic changes are not dependent on Dahl rats eating a high salt diet and do not vary as a function of salt intake.