[Effect of prolonged hypo- or hyperkinesia on the cAMP content in the liver, brain and muscles of rats].

Tested was the effect of continuous hypo- and hyperkinesia on the content of cyclic adenosine 3', 5'-monophosphate (cAMP) in some organs and tissues of rats. The experiment was carried out with a total of 18 rats, divided into three groups--control, hypokinetic, and hyperkinetic. The physical trainings were progressively prolonged. With the setting in of hypokinesia the rats were placed in cells by one for physical immobilization. The experimental period lasted 212 days. The content of cAMP was determined in samples of the liver, brain, and muscles (kept in liquid nitrogen), using the cyclic AMP assay kit--Amersham (England). It was established that continuous immobilization lowered the content of cAMP, the changes setting in being specific for the various tissues. In the liver cAMP was unreliably changed, while its level in the brain and the muscles was decreased by 28 and 36 per cent, respectively; the differences as against the data of the control group proved statistically significant. With the rats that were subjected to continuous hyperkinesia the cAMP dropped reliably in the liver (by 45 per cent) and the brain (by 53 per cent). The physical loading, however, had no effect on the level of cAMP in the skeletal muscles. The character of the changes in the cAMP content reflected to a various extent the effect of both the continuous hypokinesia and the hyperkinesia on the course of the metabolic processes in the investigated organs and tissues. Discussed is the relation between the effect of these factors on the body and the adaptational changes that set in with the adenylatecyclase--cAMP system.