Adrenocortical function in response to myocardial necrosis in exercise-trained rats.
Plasma corticosterone concentrations and in vitro adrenal secretion of corticosterone was determined in exercise-trained rats. Virgin, male rats, 100 days of age, were trained for an 11-wk period by treadmill running. Following the training program, rats were subjected to two subcutaneous injections of l-isoproterenol 24 h apart and killed 24 h after the second injection. All exercise-trained rats survived isoproterenol treatment, while 44% of the control rats died. Plasma corticosterone concentrations were elevated only in exercise-trained rats treated with isoproterenol. Control rats treated with isoproterenol had plasma corticosterone concentrations similar to that in control and exercise-treated rats given placebo injections. Exercise training reduced adrenocortical responsiveness to ACTH in vitro, but isoproterenol treatment increased in vitro responsiveness to ACTH in exercise-trained and control rats. Total unstimulated corticosterone secretion rates in vitro were similar. The reason for better rat survival in exercise-trained rats is unknown; however, improved energy metabolism, depressed aldosterone secretion, or both are suggested as reasons for the better survival of exercise-trained rats.
D000302:Adrenal Cortex / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone; D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D009202:Cardiomyopathies / Q000139:chemically induced / Q000378:metabolism* / Q000401:mortality; D003345:Corticosterone / Q000378:metabolism; D004734:Energy Metabolism; D066298:In Vitro Techniques; D007545:Isoproterenol; D008297:Male; D009336:Necrosis; D009929:Organ Size; D010805:Physical Conditioning, Animal; D051381:Rats
D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D007545:Isoproterenol; D003345:Corticosterone