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  • Title: Caffeine attenuates early post-exercise hypotension in middle-aged subjects.
    Author: Notarius CF, Morris BL, Floras JS.
    Journal: Am J Hypertens; 2006 Feb; 19(2):184-8. PubMed ID: 16448890.
    Abstract:
    BACKGROUND: Sustained hypotension after an acute dynamic exercise bout is due primarily to peripheral vasodilation. We tested the hypothesis that adenosine-mediated vasodilation contributes to hypotension after exercise, by determining the effect of blocking its actions with caffeine. METHODS: Fourteen healthy middle-aged subjects (mean age = 51 +/- 3 years), cycled to peak effort on 2 study days, after a randomized double-blind intravenous infusion of caffeine (4 mg/kg) selective for adenosine receptor blockade, or vehicle. Both studies were performed after 72 h of caffeine abstinence. RESULTS: Infusion achieved 52.0 +/- 6.1 mumol/L caffeine in plasma. Significant reductions in mean and diastolic blood pressure (BP) were elicited by prior exercise on the vehicle day (from 93 +/- 2 to 85 +/- 2 mm Hg v from 79 +/- 2 to 73 +/- 3 mm Hg, respectively; both P < .05), but not after caffeine infusion. Systolic and mean BP, 10 min after exercise, were higher on the caffeine than on the vehicle day (by 9 +/- 3 and 6 +/- 2 mm Hg, respectively; P < .05), as was heart rate (HR) (100 +/- 5 v 93 +/- 4 beats/min; P < .05). CONCLUSIONS: These data suggest that endogenous adenosine contributes to early hypotension after exercise in healthy middle-aged subjects and underscore the importance of caffeine abstinence if BP or HR immediately after exercise is used to infer cardiovascular risk.
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