SYMPATHETIC-NERVE ACTIVITY AND INSULIN SENSITIVITY IN NORMOTENSIVE OFFSPRING OF HYPERTENSIVE PARENTS

Insulin resistance and elevated sympathetic nerve activity (SNA) are o bserved in young borderline hypertensive humans. A positive family his tory of hypertension (FH) is a strong risk factor for developing hyper tension. To assess whether insulin resistance and increased sympatheti c tone precede the onset of hypertension, we studied 17 young adults w ith and 17 without a documented family history of hypertension. Subjec ts were matched for age (33 +/- 0.4 years in FH positive and 32 +/- 0. 5 years in FH negative; mean +/- SE) and body mass index (BMI, 25 +/- 1 kg/m(2) in both FH positive and FH negative subjects). We measured b lood pressure (BP), heart rate (HR), muscle sympathetic nerve activity (MSNA, microneurography), forearm blood flow, and insulin sensitivity (total glucose uptake determined by an euglycemic/hyperinsulinemic cl amp using stable isotope tracer infusion), and calculated forearm vasc ular resistance (FVR). Mean BP and HR were similar in both groups (86 +/- 3 mm Hg and 61 +/- 2 beats/min, and 85 +/- 2 mm Ng and 62 +/- 2 be ats/min, respectively, in FH positive and negative respectively, P = n s). Baseline MSNA (24 +/- 3 bursts/min in FN positive nu 20 +/- 3 burs ts/min in FH negative, P = ns) and total glucose uptake [0.104 +/- 0.0 14 mg/(kg x min x mu U insulin/mL) in FH positive nu 0.095 +/- 0.014 m g/(kg x min x mu U insulin/mL) in FH negative, P = ns] did not differ between the groups. Sympathetic and vascular responses to insulin were also similar in both groups. The increase in MSNA was 10 +/- 2 bursts /min in FN positive and 10 +/- 1 bursts/min in FH negative, P = ns. Th us, age- and weight-matched offspring with and without a FH of hyperte nsion did not vary in MSNA or insulin sensitivity. These findings sugg est that in the abscence of obesity and high arterial pressure, a FH o f hypertension may not be accompanied by decreased insulin sensitivity or increased MSNA. (C) 1998 American Journal of Hypertension, Ltd.