Regular Article
Regulation of Ground Squirrel Na+K+-ATPase Activity by Reversible Phosphorylation during Hibernation

https://doi.org/10.1006/bbrc.1998.9960Get rights and content

Abstract

Maintenance of skeletal muscle energy status during hibernation in ground squirrels,Spermophilus lateralis,was accompanied by a decrease in Na+K+-ATPase pump activity. Energy charge was maintained (0.89) during hibernation at the expense of total adenylates (decreased by 41%). Muscle Na+K+-ATPase activity was 9.1 U/mg protein in euthermic controls but decreased by 60% during hibernation. Enzyme activity was similarly suppressedin vitrowhen extracts of control muscle were incubated with ATP plus second messengers of protein kinases A, G or C whereas stimulation of protein phosphatases in muscle extracts from hibernators increased Na+K+-ATPase activity. Additional studies confirmed that suppression and reactivation of the enzyme in euthermic muscle extracts can be achieved with protein kinase A and alkaline phosphatase treatments, respectively, and indicated that phosphorylation changes the ATP dependency of the enzyme. Thus, hibernation-induced suppression of Na+K+-ATPase activity in muscle and other organs of ground squirrels, which is a key part of the overall suppression of metabolic rate that constitutes torpor, appears to be regulated via reversible protein phosphorylation.

References (29)

  • K.B. Storey

    Comp. Biochem. Physiol. A

    (1997)
  • E. Helmerhorst et al.

    Anal. Biochem.

    (1980)
  • H.J. Crombie et al.

    Comp. Biochem. Physiol. B

    (1996)
  • P. Ekman et al.

    Anal. Biochem.

    (1993)
  • A.A. Boldyrev et al.

    Biochem. Biophys. Res. Commun.

    (1996)
  • O. Lopina et al.

    Arch. Biochem. Biophys.

    (1995)
  • Z. El Hachimi et al.

    Comp. Biochem. Physiol. B

    (1990)
  • J.S. Charnock et al.

    Comp. Biochem. Physiol. B

    (1978)
  • P. Beguin et al.

    J. Biol. Chem.

    (1994)
  • L.C.H. Wang

    Advances in Comparative and Environmental Physiology

    (1989)
  • K.B. Storey et al.

    Quart. Rev. Biol.

    (1990)
  • J.E. Flanigan et al.

    J. Comp. Physiol. B

    (1993)
  • L.T. Buck et al.

    Am. J. Physiol.

    (1993)
  • J.F. Staples et al.

    Can. J. Zool.

    (1997)
  • Cited by (0)

    Wang, L. C. H.

    1

    Present address: Department of Pharmacology, Health Sciences Center, 1300 Jefferson Park Avenue, University of Virginia, Charlottesville, VA 22908.

    View full text