Effects of captopril on cold pressor test responses in normotensive and hypertensive subjects.

The aim of this study was to evaluate the effects of short-term captopril administration on the response to cold pressor testing in normotensive and hypertensive subjects. Cold pressor testing was performed in 15 normotensive subjects and 15 hypertensive patients before and 90 minutes after captopril administration. Blood pressure and heart rate were measured before testing and at one-minute intervals from the beginning of cold pressor testing. Systolic time intervals were also assessed before and after testing. Captopril did not affect pressor responses to cold pressor testing in normotensive subjects or hypertensive patients. Basal heart rate (before testing) did not change, despite the decrease in blood pressure and showed a smaller increase in response to cold pressor testing in normotensive subjects, suggesting that captopril might interfere with arterial baroreflexes. The systolic time intervals were not modified by captopril except isometric contraction time; its basal value was reduced by captopril in both normotensive subjects and hypertensive patients. Cold exposure caused a similar increase in isometric contraction time before and after captopril in normotensive subjects, and the increase in isometric contraction time in hypertensive patients was greater. These findings suggest that captopril did not affect cardiac performance, indeed improving it, at least in basal conditions.