Less adrenergic response to mental task during verapamil compared to amlodipine treatment in hypertensive subjects

We compared the effects of amlodipine and verapamil slow release on autonom ic responses to a 5-min mental arithmetic test (MST) in patients with mild to moderate hypertension. Twenty subjects received 8 weeks of verapamil slo w release 240 mg or amlodipine 10 mg in a double-blind crossover design, bo th after 4 weeks' placebo. Heart rate (HR) and blood pressure (BP) were con tinuously monitored. Venous plasma catecholamines were analysed by a radioe nzymatic assay. Baroreflex sensitivity (BRS) was estimated with the transfe r function technique. Calculations of the area under the curve (AUC) were u sed to estimate average HR, BP and catecholamine concentrations. The reacti vity to MST was estimated as percent change from the basal AUG. A paired t- test was performed. Data are means +/-SEM. Compared to verapamil, amlodipin e increased average noradrenaline (NA) concentrations (245 +/- 23 vs 191 +/ - 17 pg/l, respectively, p = 0.005), NA reactivity (14.0 +/- 5.5% vs -2.9 /- 3.3, p = 0.004), average HR (65 +/- 2 vs 61 +/- 2 beats/min, p < 0.001) and HR reactivity (2.5 +/- 1.0 vs 0.1 +/- 0.9%, p = 0.056). BP did not diff er significantly. BRS correlated with average and baseline HR on both medic ations (r = -0.53 and -0.63, p <less than or equal to> 0.03). We conclude t hat adrenergic responses to MST are blunted on treatment with verapamil com pared to amlodipine in hypertensive patients.