Comparison of the effects of four ACE inhibitors on sympathetic reactivity to cold pressor test in essential hypertensive patients

Background. We compared the effects of four different structural angiotensin-converting enzyme (ACE) inhibitors on the hemodynamic profile and catecholamine response to the cold pressor test (CPT) in hypertensive patients. Methods. We studied 44 patients with mild to moderate essential hypertension. The patients were divided into four groups according to the ACE inhibitor [enalapril (E), fosinopril (F), captopril (C), or ramipril (R)]. They were given for 8 weeks. Sympathetic reactivity was evaluated by a CPT at baseline and at the end of therapy. Blood pressure (BP), heart rate (HR), and plasma norepinephrine (NE, pg ml⁻¹) were measured at the times 0, 2, 4, 6, 8, 10, and 15 min. The delta (subtracting the basal values from the min 2 values) and the area under the curve (AUC) of the response during the CPT were studied. Results. The rise in diastolic blood pressure (DBP) (AUC) during the cold stimulus was significantly attenuated by all inhibitors studied (P<0.01): E, 17±22 to 0±20; F, 23±41 to −4±40; C, 34±33 to 7±28; R, 32±28 to −1±25. Drug therapy also blunted the response of HR to cold stress (delta HR, bpm): E, 2±2 to 0±2, P<0.05; F, 2±2 to 0±2, P<0.05; C, 3±3 to −1±3, P<0.01; R, 2±4 to −2±3, P<0.05. The rise in plasma NE (AUC) during CPT was decreased by all ACE inhibitors: E, 198±405 to 24±148, P<0.05; F, 353±436 to 51±412, P<0.05; C, 315±318 to 124±516, P<0.05; R, 677±398 to 251±307, P<0.01. Conclusions. The results in our study suggest that the blunting effects of ACE inhibitors on adrenergic tone seem to be class-dependent.