Why the study?
Does captopril or dexamethasone alter ambulatory blood pressure or day-night variability in normal male volunteers?
Does captopril or dexamethasone alter ambulatory blood pressure or day-night variability in normal male volunteers?
Short-term administration of dexamethasone does not significantly alter ambulatory blood pressure in normal subjects, suggesting the HPA axis does not play a major role in short-term BP regulation, unlike the renin-angiotensin system.
Indicates HPA axis plays limited role in short-term BP regulation in normotensives; challenges its primacy while reinforcing RAS dominance.
The role of the HPA axis in blood pressure regulation was examined in 6 normal male volunteers by comparing haemodynamic and hormonal effects of placebo, captopril, and dexamethasone given in random order for two days. The average 24-hour systolic and mean arterial pressures on placebo (135 +/- 6 and 93 +/- 2 mmHg respectively) were significantly higher than on captopril (118 +/- 1 and 85 +/- 1 mmHg respectively, p < 0.05) but there were no significant changes on dexamethasone compared with placebo (128 +/- 3 and 89 +/- 3 mmHg respectively). There were no differences in the average 24-hour diastolic blood pressures or heart rates, nor the day-night differences, night:day ratios or percentage changes in blood pressure and heart rate between treatments. Captopril significantly increased active plasma renin concentration, whilst dexamethasone decreased cortisol concentration. These results confirm the role of the renin-angiotensin system in the regulation of blood pressure in normal subjects but suggest that the HPA axis does not play a major role in determining ambulatory blood pressure or day-night variability in the short term.
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Phoon et al. (1997) studied this question.
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