[Functional characteristics of the adenylate cyclase system of developing skeletal muscles in the rat]

The functional development of hormone-sensitive adenylate cyclase system of rat skeletal muscles was studied. It was shown that within 15-17 embryonic days the plasma membrane of the muscle cell contains catecholamine-sensitive adenylate cyclase (isoproterenol greater than epinephrine greater than norepinephrine) which on these ontogenetic stages is represented by functionally active catalytic, regulatory and receptory components. The coupling component, which, according to the authors' view, is presumably an independent (fourth) functional subunit of adenylate cyclase system, is formed only in the postnatal period. A suggestion is put forward that the above process is due to the fact that guanyl nucleotide-binding protein(s) responsible in the mature target cell for the coupling of receptory and catalytic components may appear in the membrane only after birth.