Insulin resistance and Na+/K+-ATPase in hypertensive women: a difference in mechanism depending on the level of glucose tolerance

The peripheral glucose disposal rate (assessed with the euglycaemic-hyperinsulinaemic clamp technique), the serum sex hormone-binding globulin concentration and total and ouabain-sensitive 22Na-efflux rate constants in leucocytes were determined in 41 women with impaired glucose tolerance and in 40 women with normal glucose tolerance. The groups were matched for body mass index and diastolic blood pressure (range 55-112 mmHg). 2. Stepwise regression analysis showed that diastolic blood pressure in the group with impaired glucose tolerance was inversely correlated with the glucose disposal rate (model r2 = 21%) and was correlated with the plasma glucose concentration at 120 min after an oral glucose load (model r2 = 31%). In the group with normal glucose tolerance, however, neither of these two variables was correlated with blood pressure, although the ouabain-sensitive 22Na efflux rate constant was (model r2 = 11%). 3. Among insulin-resistant subjects, those with hypertension had significantly lower serum sex hormone-binding globulin concentrations than the normotensive subjects. 4. We conclude that insulin resistance is correlated with high blood pressure in women with glucose intolerance and increased androgenic activity. In women with normal insulin sensitivity, a low level of the Na+/K(+)-ATPase-mediated sodium efflux is associated with high blood pressure.