Effect of Beta-Blocker Versus Combined Alpha- and Beta-Blocker on Blood Pressure Response Under Static Exercise and Cold Pressor Test

The effect of a single oral dose of $-blocker (Metoprolol) versus combined a and R-blocker (Labetalol) was evaluated in two groups of patients; control (C) normotensive and hypertensive (H) group with mild to moderate elevation of blood pressure. Each group consisted of ten subjects. The study comprises monitoring the heart rate (HR) and blood pressure (BP) response IO two tests; hand grip test (HCT) and cold pressor test (CPT). These tests were performed before and after the drugs on separate sittings. The BP and HR response to HGT before drugs was linear for the two groups while the CPT showed insignificant rise of HR. The results at rest before and after medications in both groups showed a decrease in HR and BP. It was statistically insignificant in C-group only after labetalol. In C-group metoprolol was more effective in lowering the pressor response than labetalol while in the H-group labetalol was more potent in reducing BP specially during CPT. Introduction blood pressure by several mechanisms; reTHE treatment of primary or essential hyducing cardiac output [l], supressing the pertension involves many drug-regimens release of renin from the kidney [2] or by a separately or in combiration. Beta-blockers central action on the cerebral g-receptors are recently introduced drugs for the treatwhich mediate vasoconstriction [3] or ment of hypertension. They lower the blocking the feedback mechanism for these receptors [4 & 51.