Cyclic AMP in Developing Muscle of the Rhesus Monkey: Effect of Prostaglandin E&lt;sub&gt;2&lt;/sub&gt;

Bocek, Rose Mary; Young, Michal; Beatty, Clarissa H.

doi:10.1159/000240808

Cited by 4 publications

(4 citation statements)

References 19 publications

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“…We have reported previously that cyclic AMP levels in rhesus fetal muscle were higher than those in adult muscle (4). We now report that the level of cyclic GMP was also higher in fetal titan in adult muscle.…”

Section: Discussionmentioning

confidence: 42%

“…In rapidly growing muscle, levels of cyclic nucleotides are of particular interest since both cyclic adeno sine 3':5'-monophosphate (cyclic AMP) and cyclic guanosine 3':5'-monophosphate (cyclic GMP) appear to influence growth and differen tiation of myoblasts (16,33) and fibroblasts (19). We have previously reported that levels of cyclic AMP and adenylate cyclase activity (4,5) are higher in fetal than in adult rhesus muscle (Macaca mulatto). Many investigators believe that cyclic AMP and cyclic GMP function in biologic regulation as opposing influences (9,26), although recent evidence indicates that this hypothesis is not always true (20,21,26).…”

Section: Introductionmentioning

confidence: 99%

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Regulation of Cyclic Nucleotide Phosphodiesterase Activity in Rhesus Fetal Muscle

Beatty¹,

Herrington²,

Bocek³

1977

Neonatology

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In both fetal and adult rhesus muscle, low levels of guanosine 3’:5’-monophosphate (cyclic GMP; 0.25–5.0 μM) stimulated the adenosine 3’:5’-monophosphate (cyclic AMP)-phosphodiesterase (PDE) at low substrate levels; the fetal enzyme was more sensitive than the adult (supernatant and particulate fractions). At high levels of substrate cyclic AMP (25–100 μM), hydrolysis was not influenced by either 10 or 20 μM cyclic GMP but the fetal and adult series were equally inhibited by 40 μM cyclic GMP. In the supernatant fraction cyclic AMP inhibition of cyclic GMP hydrolysis increased with increasing cyclic AMP levels. There was no difference between fetal and adult muscle preparations in percent inhibition; however, in the adult series, the inhibition was noncompetitive whereas in the fetal series the inhibition was competitive. The K_i for cyclic AMP was 40 μM for fetal and 100 μM for adult cyclic GMP-PDE. The V_max values for cyclic GMP-PDE and both cyclic AMP-PDE enzymes were higher in the fetal series.

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Section: Discussionmentioning

confidence: 42%

Section: Introductionmentioning

confidence: 99%

Regulation of Cyclic Nucleotide Phosphodiesterase Activity in Rhesus Fetal Muscle

Beatty¹,

Herrington²,

Bocek³

1977

Neonatology

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“…We have already demonstrated that the concentration of cyclic A M P is higher in fetal than in adult skeletal muscle (7,8). Since the level of A T P and F6P at all ages is such as to ensure greater inhibition of PFK, the greater PFK activity in fetal compared with adult muscle may be due to relief of this inhibition by the higher level of cyclic A M P in the fetal tissue.…”

Section: Atp MM Mm Atp T Imentioning

confidence: 88%

“…Since cyclic A M P is an active deinhibitor of fetal PFK and the level of cyclic A M P is higher in fetal than in adult skeletal muscle (7,8), we measured the relative activities of PFK in the two series under conditions (pH 8.2) which would minimize the stimulating effect of cyclic AMP. With mammalian PFK's the enzyme generally loses its susceptibility to regulation as the pH increases above 7.6 (6).…”

Section: Atp MM Mm Atp T Imentioning

confidence: 99%

Control of Glycolysis in Skeletal Muscle from Fetal Rhesus Monkeys

1976

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A Extractregulation of glycolysis and the action of such hormones as epinephrine there is no major difference between fetal and adult muscle. In our studies of metabolic control mechanisms in skeletal muscle from rhesus fetus we have determined the tissue levels of the metabolic intermediates and cofactors of the glycolytic pathway and During the last 15 years the scarcity of data published on the have calculated the mass-action ratios for each reaction. Skeletal and biochemistry of fetal skeletal muscle contrasts muscle from rhesus fetuses (Macaca mulatta), 90-155 days of ges-with the amount of similar information on adult muscle. Studies tational age, and from adult rhesus monkeys was used in these ex-on muscle from fetal rhesus monkeys (Macaca mulatta), which are periments.biologically similar to the human primate, are therefore of he apparent equilibrium constants for hexokinase and phospho-particular interest. Although the newborn rhesus monkey appears fructokinase (PFK) in these tissues were Over 1,000 times larger to be somewhat more advanced physically than the human baby, than the mass-action ratios at all ages studied; the corresponding we have demonstrated that rhesus skeletal muscle shows a pattern values for pyruvate kinase were more than 800 times different. of differentiation into fiber types similar to that of the adult muscle The data suggest that these three enzymes are rate-limiting for at about the same relative gestational age (73% of term) as the fetal skeletal muscle as early as 54% of gestation. The next Step human muscle (75% of term) (3). Many publications are available was to study some of the numerous factors that modify these non-on the identification of rate-limiting reactions for the glycolytic equilibrium reactions. increasing the ATP concentration had a pathway in adult skeletal and cardiac muscle (20,22), but similar marked effect on the PFK activity of both fetal and adult muscle, data on fetal muscle appear to be lacking. Experimental apfirst increasing and then inhibiting enzyme activity. At maximum proaches t~ identifying regulatory enzymes in metabolic pathways PFK activity, the amount of fructose-6-PO4 (F6P) phosphorylated include determining mass-action ratios, assaying maximal enzyme per mg of protein was 2-3 times greater in the two fetal than in activities in vitro, measuring the effects of altered flux rates on the the adult series. At a concentration of 0.3 mM, citrate decreased tissue content of pathway intermediates, measuing the rates o f PFK activity of the 100-day fetal muscle; a further decrease oc-product formation from various precursors, and investigating the curred at 1.2 mM citrate. At a citrate level of 0.3 mM, the addi-kinetic and allosteric properties of enzymes, a result of such tion of inorganic phosphate ( P I ) or cyclic A M P returned PFK ac-studies, much evidence has accrued to implicate the reactions tivity to the uninhibited levels (pH 7.0). Relief of A T P inhibition of catalyzed by hexokinase, PFK, and pyruvate kinase, as regulatory F 6 P ph...

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