RELATIONSHIP BETWEEN INSULIN-RESISTANCE AND ENDOTHELIUM-DEPENDENT VASCULAR RELAXATION IN PATIENTS WITH ESSENTIAL-HYPERTENSION

The infusion of L-arginine induces the production of nitric oxide and stimulates the immediate secretion of insulin. To examine the relation ship between insulin resistance and endothelium-dependent vascular rel axation in patients with essential hypertension, we evaluated the rena l and insulin responses to L-arginine, 500 mg/kg infused intravenously over 30 minutes, in 23 patients with mild essential hypertension who were neither obese nor diabetic and in 20 normotensive control subject s. We found no difference between the two groups in blood glucose or i nsulin in the fasting condition. The renovascular relaxation induced b y L-arginine was significantly less in patients with essential hyperte nsion than in normotensive control subjects. The increase in plasma cy clic GMP in response to L-arginine was lower in hypertensive patients than in normotensive subjects. Although the serum concentrations of gl ucose in response to L-arginine were similar in the two groups, the se rum insulin response of the essential hypertensives was significantly higher than that of the normotensive subjects. In all subjects, the pe ak cyclic GMP response to L-arginine was significantly correlated with the peak Delta glucose/ Delta insulin ratio response to L-arginine (r =.69, P<.001). Findings suggested that an impairment of endothelium-de pendent renal vascular relaxation and a reduced sensitivity to insulin are present in patients with essential hypertension. A link may be pr esent between the abnormality of the L-arginine/nitric oxide/cyclic GM P pathway and insulin resistance in patients with essential hypertensi on.