Blood pressure responses to whole-body cold exposure: effect of carvedilol

Objective: The aim of this study was to test the effects of carvedilol on b lood pressure (BP) and heart rate (HR) during whole-body cold exposure in h ypertensive and normotensive subjects. Methods: Ten hypertensive and twelve normotensive subjects were exposed to cold (-15 degreesC, wind 3.5 m/s) three times for 15 min with a 1-week inte rval between the exposures. The study design was made according to a random ised double-blind, crossover method. Before the cold exposures the subjects ingested carvedilol or placebo once a day (carvedilol 12.5 mg/day for 2 da ys and then 25 mg/day for 5 days) for 1 week. The systolic (SBP) and diasto lic (DBP) blood pressure and HR were measured every 3 min during the test p rocedures using an indirect ambulatory blood pressure monitor device (ABPM- 02, Meditech Co.). Results: In the hypertensive group, the cold exposure increased SBP/DBP fro m 119/75 mmHg to 143/96 mmHg during carvedilol treatment (P < 0.001) and fr om 132/85 mmHg to 159/106 mmHg during placebo (P < 0.001). In the normotens ive group the cold exposure increased SBP/DBP from 112/72 mmHg to 142/93 mm Hg during carvedilol treatment (P < 0.001) and from 121/75 mmHg to 147/98 m mHg during placebo (P < 0.001). In the hypertensive group, the levels of SE P, DBP and MAP (mean arterial pressure) were significantly lower with carve dilol than with placebo during the cold exposure although carvedilol did no t affect the cold-induced rise of the BP. The BPs were lower also with carv edilol in the normotensive group than the placebo during the cold exposure, but the differences were smaller than in the hypertensive group. Carvedilo l decreased the BP more the higher the initial mean SBP/DBP was with placeb o during the cold exposure. Conclusion: Carvedilol reduced the BP during the cold exposure, especially in the hypertensive subjects but also in normotensive ones, without effect on the cold-induced rise of the BP.