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Hemodynamic reactivity factors to cold pressor test in blacks with sustained essential hypertension
J Toto-Moukouo1, J P Um, J P Jon
1Hypertension Research Center, Polyclinique de Douala, Fondation Soppo Priso, Cameroon.
Insights
Black African hypertensive patients and normotensive individuals respond differently to cold stress. Hypertensives show greater systolic and pulse pressure increases, suggesting distinct underlying mechanisms influencing arterial pressure reactivity.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Stress Response Studies
Background:
- Arterial pressure regulation during stress is complex.
- Understanding differences in stress response between normotensive and hypertensive individuals is crucial for cardiovascular health.
- Black African populations may exhibit unique physiological responses.
Purpose of the Study:
- To investigate factors influencing arterial pressure response to cold stress in Black African subjects.
- To compare the stress-induced arterial pressure changes in normotensive and hypertensive individuals.
- To elucidate the physiological mechanisms underlying these differences.
Main Methods:
- A cold pressor test was administered to 29 Black African subjects (11 normotensive, 18 hypertensive WHO stage I-II).
- Subjects were matched for age and body mass index.
- Arterial pressure and heart rate were monitored before and after cold exposure.
Main Results:
- Both groups exhibited increased arterial pressure post-test, with no significant heart rate change.
- Hypertensive patients showed significantly greater increases in systolic (22 vs. 16 mm Hg) and pulse pressure (8 vs. 3 mm Hg).
- Normotensive subjects had a positive correlation between systolic pressure change and heart rate change (r=+0.63).
- Hypertensive patients demonstrated a positive correlation between systolic pressure change and pulse pressure change (r=+0.52).
Conclusions:
- Arterial pressure reactivity to cold stress differs between normotensive and hypertensive individuals.
- In normotensives, parasympathetic withdrawal may be the primary mechanism.
- In hypertensives, the buffering capacity of large arteries appears to be a key factor.
Abstract:
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.