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

BACKGROUND: It has been suggested that hyperinsulinemia and insulin resistance participate in the pathogenesis of hypertension, in part by activating sympathetic activity. OBJECTIVE: 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. METHODS AND RESULTS: 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. CONCLUSIONS: 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.