ANTIHYPERTENSIVE TREATMENT WITH VERAPAMIL AND AMLODIPINE - THEIR EFFECT ON THE FUNCTIONAL AUTONOMIC AND CARDIOVASCULAR STRESS RESPONSES

Many biological and psycho logical factors induced haemodynamic and ex tra-cardiovascular functional changes mediated by the autonomic nervou s system. Pharmacological blood pressure reduction, as a neurovegetati ve stimulus, can change the arousal of the sympathetic nervous system. We evaluated the effects of two calcium channel blockers, verapamil a nd amlodipine, both administered as monotherapies, upon the sympatheti c stress response in 23 randomized mild-to-moderate essential hyperten sives (161 +/- 2/98 +/- I mmHg). Patients performed for stress tests ( mental arithmetic, colour word Stroop, cold presser and handgrip) whil e extracardiovascular and haemodynamic functions were assessed non-inv asively at every heart brat, during baseline, stress and recovery phas es. The sympathetic response was evaluated by computing the 'area-unde r-the-curve' (value x time) measured during the psychophysiological se ssion. The session was repeated at run-in, after placebo and during tr eatment. After one month's treatment, baseline blood pressure was sign ificantly reduced in patients treated with amlodipine (139 +/- 1/84 +/ - 1 mmHg; P<0.001) and verapamil (140 +/- 2/85 +/- I mmHg, P<0.001). T he emotional arousal (frontalis muscular contraction skirt conductance ) was unchanged bur the cutaneous vascular response was reduced (P<0.0 5) in patients treated with verapamil. No changes in systolic or diast olic blood pressure were detectable, but amlodipine increased the hear t rate response (P<0.05). In contrast, verapamil reduced the heart rat e (P<0.05) without depressing the cardiac output response, which was i ncreased with amlodipine (P<0.05). Total vascular resistance was signi ficantly (P<0.001) reduced with both the treatments. Consequently func tional cardiac load, expressed by pressure-rate product and cardiac po wer, was significantly enhanced with amlodipine and reduced with verap amil. In conclusion, the abnormal sympathetic stress response, which c haracterizes the hypertensive patient, might be affected by the choice of medication. Verapamil in particular, moderated emotional arousal, the vasoconstrictive response and reduced cardiac load without lowerin g cardiac output demands. In contrast, in patients treated with amlodi pine, in whom the cardiac output response was increased the pattern wa s reversed and the functional cardiac load was also increased.