Urinary Excretion of Adrenaline and Noradrenaline in Cattle During Heat and Cold Exposure

Abstract

The effects of cold and heat exposure upon the urinary excretion of adrenaline and noradrenaline were studied in the climatic laboratory on nonlactating cattle. The experimental animals were kept in a climatic chamber at 18C for 3 weeks, then exposed for 48 hours to 18, 2, 18, 37, and 18C. When the cows were exposed to 37C, urinary excretion of noradrenaline increased significantly from 59μg/24 hours at 18C to 71.6μg/24 hours at 37C. The mean adrenaline excretion was not affected.During exposure at 2C, excretion of noradrenaline was significantly increased. At 18C, urinary excretion was 58.8μg/24 hours as compared with 71.3 at 2C. Excretion of adrenaline was not significantly affected. Heat and cold exposures increased the release of noradrenaline by the sympathetic nerve endings without activation of the adrenal medulla.