Effects of amlodipine and cilnidipine on cardiac sympathetic nervous system and neurohormonal status in essential hypertension

N-Type calcium channel antagonists may suppress sympathetic activity, The p urpose of this study was to assess the effects of amlodipine and cilnidipin e on the cardiac sympathetic nervous system and the neurohormonal status of essential hypertension. I-123-metaiodobenzylguanidine (MIBG) cardiac imagi ng was performed and blood samples were taken to determine plasma renin act ivity and plasma norepinephrine concentration before and 3 months after dru g administration in 47 patients with mild essential hypertension. Twenty-fo ur 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 normo tensive subjects were also studied. No significant differences were found i n the basal characteristics between the 2 hypertensive groups. In both hype rtensive groups, both the systolic and diastolic blood pressures were signi ficantly reduced to similar levels 3 months after drug treatment. Before th e drug treatment, the 2 hypertensive groups had a significantly higher wash out rate and lower heart-to-mediastinum (H/M) ratio compared with the normo tensive subjects. The H/M ratio significantly increased (P<0.05) in combina tion with a decreased washout rate (P<0.02) after drug treatment in the cil nidipine group. In the amlodipine group, a significant decrease in washout rate (P<0.04) was noted, without an increase in the H/M ratio. However, no significant changes were found in plasma renin activity and plasma norepine phrine concentration in either group. Thus, in patients with essential hype rtension, cilnidipine suppressed cardiac sympathetic overactivity and amlod ipine had a little suppressive effect. Cilnidipine may provide a new strate gy for treatment of cardiovascular diseases with sympathetic overactivity.