Plasma and sweat histamine concentrations after heat exposure and physical exercise.

Abstract

Plasma and sweat histamine concentrations were determined in a group of healthy adult males before and after a period of daily walking on a motor-driven treadmill under hot environmental conditions. A comparison of the values before and after exercise during 10 days of repeated heat exposure was made. Plasma histamine concentrations were also determined on groups of comparable subjects before and after walking on the treadmill in a cool environment, exercises on the Universal gym (a training device designed for muscular development), and a 600-yard run. Plasma histamine concentration was found to increase significantly during exercise in hot environmental conditions and the daily increase becomes significantly less after 10 days. No changes were noted in the total sweat histamine excretion during heat exposure or the plasma histamine concentrations under the other conditions of physical exercise studied. The significance of these findings to the role of histamine in cardiovascular regulation is discussed.