MECHANISM OF MUSCULAR FATIGUE IN ADRENALECTOMIZED ANIMALS

Abstract

Despite normal muscle glycogen levels before and after exercise, well maintained, salt-treated adrenalectomized rats cannot sustain forced swimming for more than 20-40 mins. Normal rats can swim for periods longer than 2 hrs. without noticeable fatigue. In contrast to the striking difference between normal and adrenalectomized animals in the performance of sustained work in vivo, are the results of in vitro expts. obtained by stimulating (directly or indirectly) diaphragm and abdominal muscle strips from the 2 types of animals. There is no significant difference in the in vitro work performance of muscles from normal and adrenalectomized animals, even when such muscles are removed after muscular exhaustion had been induced in vivo.