Evidence of abnormalities of insulin metabolism in rats with spontaneous hypertension.

Various aspects of insulin metabolism were compared in rats with spontaneous hypertension (SHR) and a suitable control group of similar sized Kyota Wistar (WKY) rats. The results indicated that the total integrated serum insulin response to an oral glucose challenge was significantly greater in the SHR rats, despite the fact that the total integrated serum glucose responses were similar in the two groups. This indirect evidence of resistance to insulin-stimulated glucose disposal was supported by the observation that the ability of similar serum concentrations of exogenous insulin to stimulate glucose disposal was reduced in SHR rats. In addition, the metabolic clearance rate of insulin was lower in the SHR rats. These data indicate that abnormalities in insulin secretion, action, and catabolism exist in rats with spontaneous hypertension. Whether this defect is unique to SHR rats, or common to all forms of experimental hypertension, is an important issue. Equally important is the relationship between the observed changes in insulin metabolism and the elevated blood pressure.