Oscillatory behavior of glycolysis is observed when cell-free extracts of rat skeletal muscle are provided with glucose. Experimental studies and theoretical treatments have indicated that under certain conditions such oscillatory behavior can maintain a higher [ATP]/[ADP] ratio than corresponding steady state or steady flux behavior. This project will examine the effects of citrate, creatine phosphate and orthophosphate, in comparison with roles suggested by models of the oscillations. The importance of the level of glyceraldehyde 3-phosphate dehydrogenase activity in determining oscillatory or steady state behavior will be tested, as will the possibilities for interacting control of phosphorylase and phosphofructokinase with glycogen as carbon source. Spectrophotometric and fluormetric techniques will be used for continuously monitoring the system, and frequent samples will be assayed for all the glycolytic intermediates in order to follow in detail the changing pattern of the glycolytic flux under different conditions. The objective of this project is to clarify the role of specific control properties of the individual enzymes in determining the behavior of the system as a whole and to relate the complex behavior to appropriate metabolic contexts. A second objective is to obtain evidence for the occurrence of such oscillations in muscle in vivo, using very thin intact muscle and also cultured chick myotubes and rabbit aorta smooth muscle cells; sepctrophotometric and fluorometric techniques will be used, together with metabolite assays where possible.
| McCall, A L; Sussman, I; Tornheim, K et al. (1988) Effects of hypoglycemia and diabetes on fuel metabolism by rat brain microvessels. Am J Physiol 254:E272-8 |
| Tornheim, K (1988) Fructose 2,6-bisphosphate and glycolytic oscillations in skeletal muscle extracts. J Biol Chem 263:2619-24 |
| Sussman, I; Carson, M P; McCall, A L et al. (1988) Energy state of bovine cerebral microvessels: comparison of isolation methods. Microvasc Res 35:167-78 |
| McCall, A L; Valente, J; Cordero, R et al. (1988) Metabolic characterization of isolated cerebral microvessels: ATP and ADP concentrations. Microvasc Res 35:325-33 |
| McCall, A L; Fixman, L B; Fleming, N et al. (1986) Chronic hypoglycemia increases brain glucose transport. Am J Physiol 251:E442-7 |
| Tornheim, K (1985) Activation of muscle phosphofructokinase by fructose 2,6-bisphosphate and fructose 1,6-bisphosphate is differently affected by other regulatory metabolites. J Biol Chem 260:7985-9 |
