H1 and H2 receptors mediate postexercise hyperemia in sedentary and endurance exercise-trained men and women

sedentary individuals, H, receptors mediate the early portion of postexercise skeletal muscle hyperemia, whereas H-2 receptors mediate the later portion. It is not known whether postexercise hyperemia also presents in endurance-trained individuals. We hypothesized that the postexercise skeletal muscle hyperemia would also exist in endurance-trained individuals and that combined blockade of H-1 and H-2 receptors would abolish the long-lasting postexercise hyperemia in trained and sedentary individuals. We studied 28 sedentary and endurance trained men and women before and through 90 min after a 60-min bout of cycling at 60% peak O-2 uptake on control and combined H-1- and H-2-receptor antagonist days (fexofenadine and ranitidine). We measured arterial pressure (brachial auscultation) and femoral blood flow (Doppler ultrasound). On the control day, femoral vascular conductance (calculated as flow/pressure) was elevated in all cups 60 min after exercise (sedentary men: Delta 86 +/- 35%, trained men. Delta 65 +/- 18%; sedentary women, Delta 61 +/- 19%, trained women: Delta 59 +/- 23%. where A is change; all P < 0.05 vs. preexercise). In contrast. on the histamine antagonist day, femoral vascular conductance was not elevated in any of the groups after exercise (sedentary men: Delta 21 +/- 17%, trained men: Delta 9 +/- 5%, sedentary women: Delta 19 +/- 4%. trained women: Delta 11 +/- 11%; all P > 0.16 vs. preexercise; all P < 0.05 vs. control day). These data suggest postexercise skeletal muscle hyperemia exists in endurance trained men and women. Furthermore, histaminergic mechanisms produce the long-lasting hyperemia in sedentary and endurance-trained individuals.