Histamine-receptor blockade reduces blood flow but not muscle glucose uptake during postexercise recovery in humans

Skeletal muscle vasodilatation persists following a single bout of exercise and can potentially influence glucose uptake by recovering muscle. To investigate whether blood flow is a rate-limiting component in postexercise muscle glucose uptake, we tested the hypothesis that oral ingestion of H(1)- and H(2)-receptor antagonists, known to attenuate the sustained postexercise vasodilatation, would reduce leg glucose uptake after a bout of cycling. Healthy, recreationally active subjects (n = 8) exercised for 1 h at 60% of peak oxygen consumption on each of two days, with (blockade) and without (control) histamine-receptor antagonism. For 2 h of recovery following exercise, arteriovenous glucose differences were assessed from the radial artery and femoral vein, and leg blood flow was measured using Doppler ultrasonography on the common femoral artery. Femoral blood flow following exercise was 65.4 +/- 16.4 ml min(-1) lower on the blockade day compared with the control day (P < 0.05). Likewise, glucose delivery was 0.177 +/- 0.045 mmol min(-1) lower with blockade (P < 0.05). However, histamine-receptor antagonism produced no consistent effect on leg glucose uptake following exercise, due to high interindividual variability. In conclusion, while oral ingestion of H(1)- and H(2)-receptor antagonists alters postexercise recovery by attenuating vasodilatation, leg glucose uptake is not universally affected in recreationally active individuals.