Insulin sensitivity, sodium-lithium countertransport and platelet free calcium concentrations in normotensive men with a family history of hypertension

Abstract

Peripheral glucose disposal (assessed with the euglycaemic-hyperinsulinaemic clamp technique), Na⁺-Li⁺ countertransport in erythrocytes and the cytosolic free Ca²⁺ concentration in platelets were determined in 36 men from families with essential hypertension in at least two close relatives and in 28 age- and weight-matched men from families without hypertension. All had diastolic blood pressure consistently below 90 mm Hg and a normal oral glucose tolerance test. The mean age of the study population as a whole was 37 years (range 24–46). Insulin sensitivity index values (glucose disposal/serum insulin concentration during the clamp) were lower in the familial hypertension group than in the control group, but the two groups did not differ in Na⁺-Li⁺-countertransport, or in the platelet cytosolic free Ca²⁺ concentration which was correlated to the waist: hip circumference ratio in both groups (r = 0.38 and r = 0.49, respectively). The present findings do not support the hypothesis that an increase in Na⁺-Li⁺ countertransport activity or the platelet cytosolic free Ca²⁺ concentration is a marker of insulin resistance in hypertension prone men.