Relationship between insulin resistance and cardiac sympathetic nervous function in essential hypertension

Background It has been suggested that hyperinsulinemia and insulin resistan ce participate in the pathogenesis of hypertension, in part by activating s ympathetic activity. Objective We aimed to examine the relationship between insulin resistance a nd cardiac sympathetic nervous function in patients with essential hyperten sion using I-123-metaiodobenzylguanidine (MIBG) cardiac scintigraphy. Methods and results Twenty-eight patients (18 men) with essential hypertens ion and 11 (seven men) control individuals with a mean age of 55.8 +/- 3.3 years were recruited. Patients with diabetes mellitus, congestive heart fai lure or coronary artery disease were excluded from this study. To evaluate insulin resistance, we used steady-state plasma glucose (SSPG; mg/dl) level s measured by the SSPG method. To evaluate cardiac sympathetic nervous func tion, we calculated the heart-to-mediastinum ratio from the delayed MIBG im age (H:M-D) and the mean washout rate (WOR, %). There were significant diff erences (P < 0.01) in SSPG, H :M-D and WOR between the essential hypertensi on and control individual groups (125 versus 103 mg/dl, 2.2 versus 2.4, and 32 versus 23%, respectively). Stepwise regression analysis showed that SSP G and plasma norepinephrine level are independent predictors for the cardia c sympathetic nervous function obtained from MIBG scintigraphy. Conclusions These findings indicate that insulin resistance is significantl y related to activation of the cardiac sympathetic nervous function associa ted with left ventricular hypertrophy in patients with essential hypertensi on. J Hypertens 1999, 17:1161-1168 (C) Lippincott Williams & Wilkins.