Control of Glycolysis in Skeletal Muscle from Fetal Rhesus Monkeys

Abstract

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...

Perinatal Changes in Glycolytic Function in Response to Hypoxia in the Incubated or Perfused Rat Heart

“…The increase of tissue lactate up to 29 ju/W/g in the normoxic incubated hearts of 21.5 dpc and the probable concomitant decrease of intracellular pH (15,25) could also account for inhibited glycolysis. A regulatory role of PFK in glycolysis has also been recently reported early in gestation in the skeletal muscle (3).…”

Proteins Associated with Thermally Induced Gelation of Turkey Breast Meat

“…The finding that an increased presence of pyruvate kinase in the SSP is associated with decreased gel elasticity and the finding that an increased presence of triose phosphate isomerase in the salt‐insoluble fraction is associated with decreased gel elasticity support the hypothesis that metabolic activity postharvest affects the ultimate functionality of meat. Pyruvate kinase is proposed to be one of the rate‐limiting steps in glycolysis (Beaty and others 1976). In addition, reduced oxygen levels have been hypothesized to slow the biodegradation rate of pyruvate kinase (Hance and others 1980).…”

Pioglitazone improves phagocytic activity of liver recruited macrophages in elderly mice possibly by promoting glucose catabolism

“…34 We found that liver recruited Mu in pioglitazone-treated mice enhanced expressions of genes encoding rate-limiting enzymes involved in glycolysis (phosphofructokinase, pyruvate kinase, and hexokinase-1). 35 Furthermore, they ingested larger numbers of bacteria, which was abrogated by the inhibition of glycolysis or OXPHOS. These results suggest that pioglitazone might increase the phagocytic and bactericidal activities of liver recruited Mu by regulating their metabolic catabolism, especially of glucose.…”