The Content of Adenosinetriphosphate and Creatine Phosphate in Uterine Muscle of Rats and Rabbits.

Summary. The content of acid soluble phosphate compounds in uterine muscle of rats and rabbits have been determined. Relatively low content of adenosinetriphosphate (ATP) and creatine phosphate (PC) were found in uterine muscle. The mean values of ATP were about 2 mg per 100 g and of PC about 1 mg per 100 g wet muscle tissue. The content of ATP was approximately 1/20 and of PC 1/50 of these substances in skeletal muscle. Injection with estradiolbenzoate or estradiolbenzoate + progesterone had no significant effect on the content of ATP and PC in uterine muscle. A slight increase in tbe content of ATP of uterine muscle was found during the last part of pregnancy in rats, of marginal statistical significance. The results have been discussed in relation to physiological activity. It has been suggested that the low content of phosphate compounds may be of importance to the time factor and the force in uterine muscle contraction.