Correlation of sodium-related factors with insulin sensitivity in young, lean, male offspring of hypertensive and normotensive subjects

Pioneer studies have proposed that multiple metabolic abnormalities, such a s insulin resistance, increased Na+-H+ exchanger activity and abnormal intr acellular calcium homeostasis, are frequently associated with a subset of e ssential hypertensive patients with low plasma renin activity (PRA). Howeve r, it is unclear whether insulin resistance is related to the low renin sta tus in the very early phase of genetical hypertension. Besides, there is co ntroversy on the subject of the in vivo effect of acute hyperinsulinaemia o n sodium-related factors. We investigated the relationship between sodium-r elated parameters and insulin sensitivity, and the effects of euglycaemic h yperinsulinaemia on cyclic guanosine monophosphate (cGMP) and atrial natriu retic peptide (ANP) levels in 17 young, lean, normotensive male subjects, w ho displayed extreme predispositions for the development of hypertension. P RA was significantly lower in the positive than in the negative family hist ory group (P < 0.05). Insulin sensitivity (M-value) was correlated with PRA before euglycaemic hyperinsulinaemic clamping (r = 0.577, P < 0.05), and w as also inversely correlated with fractional excretion of sodium (FENa) bef ore clamping (r = -0.51, P < 0.05). Euglycaemic hyperinsulinaemia significa ntly decreased PRA (P < 0.0001) and increased cGMP (P < 0.05) and ANP level s (P <less than> 0.01). In conclusion, insulin sensitivity may be partially determined by PRA levels and FENa before clamping in young, lean, normoten sive male subjects. Acute euglycaemic hyperinsulinaemia decreases PRA, and increases cGMP and ANP levels from the fasting condition.