Effects of Amlodipine and Cilnidipine on Cardiac Sympathetic Nervous System and Neurohormonal Status in Essential Hypertension

Abstract —N-Type calcium channel antagonists may suppress sympathetic activity. The purpose of this study was to assess the effects of amlodipine and cilnidipine on the cardiac sympathetic nervous system and the neurohormonal status of essential hypertension. 123 I-metaiodobenzylguanidine (MIBG) cardiac imaging was performed and blood samples were taken to determine plasma renin activity and plasma norepinephrine concentration before and 3 months after drug administration in 47 patients with mild essential hypertension. Twenty-four of the patients were treated with 5 to 10 mg/d of amlodipine; the other 23 were treated with 10 to 20 mg/d of cilnidipine. For comparison, 12 normotensive subjects were also studied. No significant differences were found in the basal characteristics between the 2 hypertensive groups. In both hypertensive groups, both the systolic and diastolic blood pressures were significantly reduced to similar levels 3 months after drug treatment. Before the drug treatment, the 2 hypertensive groups had a significantly higher washout rate and lower heart-to-mediastinum (H/M) ratio compared with the normotensive subjects. The H/M ratio significantly increased ( P P P