Abnormalities in Insulin Sensitivity, Vascular Resistance and Erythrocyte Cation Transport are Independent Genetic Traits in Familial Hypertension

Abstract

Several isolated abnormalities have been noted in normotensive members of hypertensive families, including exaggerated forearm vascular resistance (FVR), decreased insulin sensitivity and elevated sodium-lithium (Na/Li) countertransport. No family study has investigated the aforementioned abnormalities concurrently within the same hypertensive families. It is therefore unknown whether these disturbances reflect single or different genetic traits. Thus, we studied cardiovascular reactivity of the forearm vasculature, cellular sodium transport mechanisms and insulin sensitivity concomitantly in normotensive (n = 24) and borderline hypertensive (n = 16) members of hypertensive families, compared with normotensive members (n = 24) of normotensive families. At least one abnormality was noted in 27 (67%) out the 40 subjects with a positive family history of hypertension. Na/Li-countertransport was increased in 15 (37%), FVR was increased in 14 (35%) and insulin sensitivity was decreased in 9 (22%) subjects with familial hypertension. The concomitant occurrence of at least 2 out of the 3 abnormalities mentioned was noted in 9 (22%) out of the 40 subjects with family history of hypertension. Decreased insulin sensitivity, increased basal FVR and increased Na/Li countertransport were concurrently observed in two (5%) subjects. This investigation documents the frequent occurrence of abnormalities such as decreased insulin sensitivity, increased basal FVR and Na/Li-countertransport in subjects with family history of hypertension. The concomitant occurrence of at least two of the mentioned abnormalities being observed in less than one-quarter of the subjects with family history of essential hypertension, it is assumed that insulin sensitivity, basal FVR and Na/Li-countertransport reflect more than one genetic trait predisposing to hypertension.