RESUMO
The purpose of this study was to evaluate the effects of antihypertensive drugs on renal hemodynamics in hypertensive patients during an adrenergic activation by mental stress (MS), which induces renal vasoconstriction in healthy subjects. Renal hemodynamics was assessed twice in 30 middle-aged essential hypertensive patients (57±6 years)-after 15 days of pharmacological wash-out and after 15 days of treatment with Trandolapril (T, 4 mg, n=10), Verapamil (V, 240 mg, n=10), or both (T 2 mg+V 180 mg, n=10). Each experiment consisted of 4 30-min periods (baseline, MS, recovery I and II). Renal hemodynamics was evaluated with effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) from plasminogen activator inhibitor and inulin clearance, respectively. MS increased blood pressure (BP) to a similar extent before and after each treatment. Before treatment, the increasing BP was not associated with any modification of ERPF in the 3 groups. Renal vascular resistances (RVR) markedly increased during MS (+23% in the T group, +21.6% in the V group, and +32.9% in the T+V group); GFR remained constant during the whole experiment. After treatment, ERPF decreased significantly during MS in the T group (-15%, P<0.05) and in the V group (-11.7%, p<0.01); in the T+V group, ERPF modifications were not statistically significant (P=0.07). In the T group, ERPF reverted to baseline values at the end of the stimulus, whereas in the V group, renal vasoconstriction was more prolonged. Only in hypertensive patients treated with 4 mg of T, RVR reverted to baseline during the recovery I, whereas in the V group, RVR remained elevated for the whole experiment. No modifications of GFR were observed in all groups. The kidney of hypertensive patients cannot react to a sympathetic stimulus with the physiological vasoconstriction. A short-term antihypertensive treatment with 4 mg of T restores the physiological renal response to adrenergic activation.
