HEMODYNAMIC REACTIVITY FACTORS TO COLD PRESSOR TEST IN BLACKS WITH SUSTAINED ESSENTIAL-HYPERTENSION

To evaluate factors that might influence arterial pressure response to stress, 29 black African subjects were submitted to a cold pressor test. Eleven of them were normotensive healthy subjects, and 18 were hypertensive patients (WHO stage I to II). Both groups were matched in age (41 +/- 3 years and 42 +/- 3 years, respectively) and body mass index (25 +/- 2.10(-4) kg/cm2). After the cold pressor test, both groups showed a significant increase in arterial pressure, but not in heart rate absolute value. Considering the level of change in each parameter, only systolic and pulse pressure showed significant increases in hypertensive patients (respectively 16 +/- 5 mm Hg v 22 +/- 3 mm Hg, P < .02 and 3 +/- 1 mm Hg v 8 +/- 2 mm Hg, P < .01). An inverse relationship was shown in both study populations: change in systolic arterial pressure was positively and significantly correlated to the change in heart rate (r = +0.63, P < .02), but not to the change in pulse pressure (r = 0.34, P = NS) in normotensive subjects. Inversely, in hypertensive patients there was a positive and significant correlation with the change in pulse pressure (r = +0.52, P < .01), but not with the change in heart rate. We conclude that arterial pressure reactivity to the cold pressor test might be influenced by different mechanisms in normotensives and hypertensives. In the former, the withdrawal of parasympathetic tone might be the main factor, whereas in hypertensives, the cushioning of function of large arteries might be the principal factor.