Progressive Enhancement of Body Temperature Responses to Consecutive Exercise-Bouts of the Same Intensity in Dogs

摘要

Progressive enhancement of body temperature responses to consecutive exercise-bouts of the same intensity in dogs. Changes in rectal (T(sub re)) muscle (T(sub m)), and hypothalamic (T(sub hy)) temperatures, plasma osmolality, and some intermediary metabolic variables were examined in dogs performing four successive exercise-bouts of the same intensity. During the rest-intervals separating the exercise-bouts body temperatures returned to initial levels and water losses were replaced. T(sub m) and T(sub re) responses to consecutive exercise-bouts were progressively increasing. Similar tendency was found in T(sub hy) changes. Cardiac and respiratory frequencies attained the same level in all four exercise-bouts, while blood lactate and FFA concentrations were increasing and blood glucose level was decreasing progressively. No changes in plasma osmolality was noted. Exercise-induced increases in Tm correlated positively with plasma FFA concentration (r=0.68). Body temperature responses to exercise were reduced by beta-adrenergic blockage. It is concluded that the enhancement of the thermal responses to consecutive exercise-bouts can be related to the metabolic action of catecholamines.