EFFECTS OF MUSCULAR WORK ON CORTISOL AND CORTICOSTERONE CONTENT IN THE BLOOD AND ADRENALS OF GUINEA PIGS

Abstract

The cortisol and corticosterone content was determined fluorometrically in the blood and in the adrenals of guinea pigs. After three 5-minute-swimming sets the corticoid content increased in the adrenals, but remained unchanged in the blood. After 5-minute-swimming sets repeated until exhaustion, the adrenal corticoid content did not differ from the level of the control group. The blood cortisol content, however, fell significantly. The blood corticosterone content did not change. If before the swimming sets 4 IU of corticotrophin were administered, the cortisol content both in the adrenals and blood at the point of exhaustion was somewhat higher than in the control group. The decrease in blood corticoid concentration during long-lasting muscular work is due to insufficient stimulation of the adrenocortical activity. It has been suggested that the inhibition of the stimulation of the adrenocortical activity is one manifestation of a general defence reaction, against the fatal depletion of the resources of the organism.