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Hemodynamic and humoral effects of caffeine in autonomic failure. Therapeutic implications for postprandial
Insights
Caffeine raises blood pressure and prevents significant drops after meals in patients with autonomic failure. This effect is not linked to increased stress hormones or the renin-angiotensin system, suggesting caffeine may treat hypotension.
Area of Science:
- Cardiology
- Neurology
- Pharmacology
Background:
- Autonomic failure can cause significant blood pressure drops after meals (postprandial hypotension).
- Caffeine is a widely consumed stimulant with known cardiovascular effects.
Purpose of the Study:
- To investigate the effects of caffeine on blood pressure and heart rate in patients with autonomic failure.
- To determine if caffeine influences hormonal responses (norepinephrine, epinephrine, renin activity) related to blood pressure regulation.
- To assess caffeine's ability to mitigate postprandial hypotension in this patient group.
Main Methods:
- Twelve patients with autonomic failure were studied.
- Blood pressure, heart rate, plasma norepinephrine, epinephrine, and renin activity were measured.
- Effects of a 250 mg caffeine dose and a standardized meal were assessed, both independently and after caffeine pre-treatment.
Main Results:
- Caffeine (250 mg) increased blood pressure by 12/6 mm Hg but did not affect heart rate or key hormones.
- A standardized meal caused a significant drop in blood pressure (28/18 mm Hg).
- Caffeine pre-treatment attenuated the meal-induced blood pressure fall (11/10 mm Hg) and maintained higher postprandial blood pressures.
Conclusions:
- Caffeine acts as a pressor agent and effectively reduces postprandial hypotension in autonomic failure.
- This effect appears independent of significant changes in sympathoadrenal activity or the renin-angiotensin system.
- Caffeine shows potential as a therapeutic agent for orthostatic hypotension, particularly in the postprandial state, associated with autonomic failure.
Abstract:
We examined the effects of caffeine and meals on blood pressure and heart rate in 12 patients with autonomic failure. The influence of caffeine on plasma norepinephrine, epinephrine, and renin activity was also studied. Caffeine 250 mg, raised blood pressure by 12/6 mm Hg, from 129 +/- 25/78 +/- 12 (mean +/- S.D.) to a maximum of 141 +/- 30/84 +/- 16 mm Hg at 45 minutes (P less than 0.01), but did not change heart rate, levels of norepinephrine, or epinephrine, or plasma renin activity. Blood pressure fell by 28/18 mm Hg after a standardized meal, from 133 +/- 32/80 +/- 15 to a minimum of 105 +/- 21/62 +/- 12 mm Hg at 60 minutes (P less than 0.01). After pretreatment with 250 mg of caffeine, the standardized meal induced a fall of only 11/10 mm Hg, from 140 +/- 33/79 +/- 7 to 129 +/- 31/69 +/- 13 mm Hg at 60 minutes (P less than 0.05 vs. values after the control per day for seven days) in five patients, postprandial blood pressures remained higher after caffeine than after placebo (P less than 0.05). We conclude that caffeine is a pressor agent and attenuates postprandial hypotension in autonomic failure, and that this effect is not primarily due to elevations in sympathoadrenal activity or activation of the renin-angiotensin system. Caffeine may be useful in the treatment of orthostatic hypotension due to autonomic failure, especially in the postprandial state.