Ontogenetic changes in adenylate cyclase, cyclic AMP phosphodiesterase and calmodulin in chick ventricular myocardium.
The activities of cyclic AMP phosphodiesterase (3',5'-cyclic nucleotide 5'-nucleotidohydrolase, EC 3.1.4.17) and adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and calmodulin content during development of chick ventricular myocardium were determined. The specific activity of cyclic AMP phosphodiesterase was relatively low in early embryos, increased during embryogenesis by about 4-fold to reach highest values just before hatching, and then decreased by approx. 30% within 1 week after hatching. In contrast, adenylate cyclase did not change during embryonic development, but increased by approx. 50% within 1 week after hatching. Calmodulin content remained constant at 9 micrograms/g wet wt. during embryonic development and decreased to 6 micrograms/g wet wt. by 1 week after hatching. DEAE-Sephacel chromatography of chick ventricular supernatant revealed a single major form of cyclic nucleotide phosphodiesterase activity in early embryonic (9-day E) and hatched (6-day H) chicks. This enzyme form was eluted at approx. 0.27 M-sodium acetate, hydrolysed both cyclic AMP and cyclic GMP, and was sensitive to stimulation by Ca2+-calmodulin, with an apparent Km for calmodulin of approx. 1 nM. In contrast, ventricular supernatant from late-embryonic (18-day E) chicks contained two forms of phosphodiesterase separable on DEAE-Sephacel: the same form as that seen at other ages, plus a cyclic AMP-specific form which was eluted at approx. 0.65 M-sodium acetate and was insensitive to stimulation by Ca2+-calmodulin. The ontogenetic changes in cyclic AMP phosphodiesterase activity in chick ventricular myocardium are consistent with reported ontogenetic changes in the steady-state contents of cyclic AMP in this tissue and suggest that this enzyme may be responsible for the changes that occur in this nucleotide during development of chick myocardium.
Epstein
P M
PM
Andrenyak
D M
DM
Smith
C J
CJ
Pappano
A J
AJ
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000378:metabolism*; D002642:Chick Embryo; D002645:Chickens; D002852:Chromatography, Ion Exchange; D000242:Cyclic AMP / Q000378:metabolism; D006321:Heart / Q000187:drug effects / Q000254:growth & development; D009206:Myocardium / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism
D002147:Calmodulin; D011506:Proteins; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D002118:Calcium