Journal of Comparative Physiology B

, Volume 162, Issue 1, pp 23–28

Mechanisms of glycolytic control during hibernation in the ground squirrel Spermophilus lateralis

  • Stephen P. J. Brooks
  • Kenneth B. Storey
Article

DOI: 10.1007/BF00257932

Cite this article as:
Brooks, S.P.J. & Storey, K.B. J Comp Physiol B (1992) 162: 23. doi:10.1007/BF00257932

Summary

The mechanisms of glycolytic rate control during hibernation in the ground squirrel Spermophilus lateralis were investigated in four tissues: heart, liver, kidney, and leg muscle. Overall glycogen phosphorylase activity decreased significantly in liver and kidney to give 50% or 75% of the activity found in the corresponding euthermic organs, respectively. The concentration of fructose-2,6-bisphosphate (F-2,6-P2) decreased significantly in heart and leg muscle during hibernation to 50% and 80% of euthermic tissue concentrations, respectively, but remained constant in liver and kidney. The overall activity of pyruvate dehydrogenase (PDH) in heart and kidney from hibernators was only 4% of the corresponding euthermic values. Measurements of phosphofructokinase (PFK) and pyruvate kinase (PK) kinetic parameters in euthermic and hibernating animals showed that heart and skeletal muscle had typical rabbit skeletal M-type PFK and M1-type PK. Liver and kidney PFK were similar to the L-type enzyme from rabbit liver, whereas liver and kidney PK were similar to the M2 isozyme found primarily in rabbit kidney. The kinetic parameters of PFK and PK from euthermic vs hibernating animals were not statistically different. These data indicate that tissue-specific phosphorylation of glycogen phosphorylase and PDH, as well as changes in the concentration of F-2,6-P2 may be part of a general mechanism to coordinate glycolytic rate reduction in hibernating S. lateralis.

Key words

Hibernation Control of glycolysis Phosphofructokinase Pyruvate kinase Pyruvate dehydrogenase Spermophilus lateralis 

Abbreviations

ADP

adenosine diphosphate

AMP

adenosine monophosphate

ATP

adenonine triphoshate

EDTA

ethylenediaminetetra-acetic acid

EGTA

ethylene glycol tetra-acetic acid

F-6-P

fructose 6-phosphate

F-1,6-P2

fructose 1,6-bisphosphate

F-2,6-P2

fructose-2,6-bisphosphate

Ka

activation coefficient

I50

concentration of inhibitor which reduces control activity by 50%

PDH

pyruvate dehydrogenase

PEP

phosphoenolpyruvate

PFK

6-phosphofructo-1-kinase

PK

pyruvate kinase

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Stephen P. J. Brooks
    • 1
    • 2
  • Kenneth B. Storey
    • 1
    • 2
  1. 1.Institute of BiochemistryCarleton UniversityOttawaCanada
  2. 2.Department of BiologyCarleton UniversityOttawaCanada

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