[The peptide activator of cyclic nucleotide phosphodiesterases: its effect on muscle contractile activity].

The presence of the peptide activator of cyclic nucleotide phosphodiesterase, which has been discovered previously in rat and calf myometrium, was studied in different rat tissues. The peptide was shown to present only in muscle tissues, except for intestinal tissue. In physiological experiments the peptide stimulated the contraction of rat uterine smooth muscle and diaphragmatic muscle. Phosphodiesterase inhibitors reduced this effect of the peptide. It is suggested that the effects of peptide are related to the changes in cyclic nucleotide levels in consequence of phosphodiesterase activation. Peptide did not change the activity of uterine adenylate cyclase.