Role of fructose-2,6-bisphosphate in cardiac glycolysis
To study whether changes in the content of fructose-2,6-bisphosphate (Fru-2,6-P/sub 2/) are important in the control of phosphofructokinase (PFK) and glycolysis in heart. As in liver, isolated rat hearts were perfused as either a Langendorff or working model with various glucose concentrations in the presence or absence of insulin. Glucose utilization was estimated from /sup 3/H/sub 2/O production from (3-/sup 3/H)glucose. Metabolite contents were measured and PFK was isolated from freeze-clamped hearts. Both cardiac work and insulin accelerated glycolysis 4 to 6 fold. Cellular contents of allosteric effects of PFK including ATP, AMP, Pi, Fru-1,6-P/sub 2/, and cytoplasmic citrate did not change or correlate with these increased rates. Increases in Fru-6-P availability and Fru-2,6-P/sub 2/ did appear to correlate with increased glycolytic rate. Higher Fru-6-P appeared more important in regulating the rate increase observed with insulin in Langendorff hearts, while Fru-2,6-P/sub 2/ appeared more important in mediating the increased rate seen with higher workload. In addition, PFK isolated from working hearts was less sensitive to ATP inhibition than PFK from Langendorff hearts. It is concluded that changes in Fru-6-P, Fru-2,6-P/sub 2/, and a covalent modification are important in the control of PFK activity and glycolysis in heart muscle, but the relative importance of the contributions appears to depend on the stimulus. The classic effectors of PFK activity probably play no role in such control.
- Research Organization:
- VA Medical Center, Dallas, TX
- OSTI ID:
- 7170698
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
BIOCHEMICAL REACTION KINETICS
BODY
CARBOHYDRATES
CARDIOVASCULAR SYSTEM
ENZYME ACTIVITY
ENZYMES
FRUCTOSE
GLUCOSE
HEART
HEXOSES
HORMONES
HYDROGEN COMPOUNDS
INSULIN
ISOTOPE APPLICATIONS
KETONES
KINETICS
LABELLED COMPOUNDS
METABOLISM
METABOLITES
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PEPTIDE HORMONES
PERFUSED ORGANS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
REACTION KINETICS
SACCHARIDES
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS
WATER