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

Abstract

It has been suggested that hyperinsulinemia and insulin resistance participate in the pathogenesis of hypertension, in part by activating sympathetic activity. We aimed to examine the relationship between insulin resistance and cardiac sympathetic nervous function in patients with essential hypertension using 123I-metaiodobenzylguanidine (MIBG) cardiac scintigraphy. Twenty-eight patients (18 men) with essential hypertension and 11 (seven men) control individuals with a mean age of 55.8+/-3.3 years were recruited. Patients with diabetes mellitus, congestive heart failure or coronary artery disease were excluded from this study. To evaluate insulin resistance, we used steady-state plasma glucose (SSPG; mg/dl) levels measured by the SSPG method. To evaluate cardiac sympathetic nervous function, we calculated the heart-to-mediastinum ratio from the delayed MIBG image (H:M-D) and the mean washout rate (WOR, %). There were significant differences (P<0.01) in SSPG, H:M-D and WOR between the essential hypertension and control individual groups (125 versus 103 mg/dl, 2.2 versus 2.4, and 32 versus 23%, respectively). Stepwise regression analysis showed that SSPG and plasma norepinephrine level are independent predictors for the cardiac sympathetic nervous function obtained from MIBG scintigraphy. These findings indicate that insulin resistance is significantly related to activation of the cardiac sympathetic nervous function associated with left ventricular hypertrophy in patients with essential hypertension.