Catecholamine and cortisol responses of horses to incremental exertion.

摘要

Plasma concentrations of catecholamines and cortisol were measured in horses in response to different levels of exertion. Plasma cortisol, epinephrine and norepinephrine increased significantly (p < 0.05) with exertion. The plasma cortisol concentrations at relative work intensities of 48.3% ?1.4%, 82.3% ?2.0% and 99.6% ?0.4% of VO2max were 114%, 124%, and 126%, respectively, of those at rest, whereas the plasma epinephrine concentrations were 239%, 772% and 3483%, and the norepinephrine concentrations were 138%, 255%, and 1121% of the values at rest. There was a significant (p < 0.0001) relationship between the plasma epinephrine and norepinephrine concentrations. The blood lactate concentration and the plasma epinephrine and norepinephrine concentrations were significantly (p < 0.0001) related, as were the relative work intensity (% VO2max) and the plasma epinephrine and norepinephrine concentrations. The relationships between the plasma cortisol concentration and work intensity or blood lactate concentration were not significant (p > 0.05). These results identify a relationship between relative work intensity and indicators of adrenal medullary and sympathetic activity during brief exertion in horses.