[System for effecting the action of cyclic adenosine monophosphate in skeletal muscle during chicken ontogeny]

Studies have been made on the possibility of realization of cAMP regulatory action on carbohydrate and calcium metabolism of skeletal muscles in chick embryos. It was shown that during embryonic period cAMP does not activate phosphorylase system and does not inhibit glycogen synthetase. It was found that the absence of any influence of cAMP on these enzymes of carbohydrate metabolism in embryonic muscles does not depend on the state of cAMP-dependent protein kinase, since this enzyme is functionally active. In contrast to the enzymes of carbohydrate metabolism, Ca2+, Mg2+-ATPase of sarcoplasmic reticulum is sensitive to stimulation by cAMP at least from the 2nd week of embryonic development. It is concluded that embryonic skeletal muscles of chicks exhibit all the conditions which are necessary for realization of the regulatory effect of cAMP. Yet the realization of any effect of the nucleotide depends on the maturity of the given effector link.