Effects of caffeine on baroreflex activity in humans

• Published in: Clinical pharmacology and therapeutics Vol. 48; no. 5; p. 568
• Main Authors: Mosqueda-Garcia, R, Tseng, C J, Biaggioni, I, Robertson, R M, Robertson, D
• Format: Journal Article
• Language: English
• Published: United States 01.11.1990
• Subjects: Administration, Oral; Adult; Blood Pressure - drug effects; Caffeine - administration & dosage; Caffeine - blood; Caffeine - pharmacology; Heart Rate - drug effects; Humans; Male; Pressoreceptors - drug effects; Reflex - drug effects
• ISSN: 0009-9236
• DOI: 10.1038/clpt.1990.193

The effects of caffeine or placebo on blood pressure, heart rate, and baroreflex activation (elicited by phenylephrine) were studied on young normotensive volunteers after a 7-day caffeine-free period. Subjects received oral doses of either 250 mg caffeine (n = 6) or placebo (n = 4), and hemodynamic changes were studied at 0, 30, 60, 120, and 180 minutes after drug administration. Thirty minutes after the caffeine dose, blood pressure had risen from 127 +/- 8/57 +/- 4 mm Hg to 136 +/- 3/68 +/- 5 mm Hg, heart rate was unchanged, and the baroreflex slope had decreased from 31 +/- 7 msec/mm Hg to 11.6 +/- 2 msec/mm Hg. Baroreflex sensitivity remained inhibited for the rest of the single-dose experimental period. In contrast, no significant changes were observed after either long-term caffeine ingestion in the same group or in the placebo group during the single- or multiple-dose study. These findings indicate that single but not multiple caffeine administration inhibits baroreflex activation in normotensive volunteers and this could contribute to the acute hemodynamic effects of caffeine.