Journal of Comparative Physiology B

, Volume 187, Issue 1, pp 227–234

Regulation of mitochondrial metabolism during hibernation by reversible suppression of electron transport system enzymes

  • Katherine E. Mathers
  • Sarah V. McFarlane
  • Lin Zhao
  • James F. Staples
Original Paper

DOI: 10.1007/s00360-016-1022-0

Cite this article as:
Mathers, K.E., McFarlane, S.V., Zhao, L. et al. J Comp Physiol B (2017) 187: 227. doi:10.1007/s00360-016-1022-0

Abstract

Small hibernators cycle between periods of torpor, with body temperature (Tb) approximately 5 °C, and interbout euthermia (IBE), where Tb is approximately 37 °C. During entrance into a torpor bout liver mitochondrial respiration is rapidly suppressed by 70 % relative to IBE. We compared activities of electron transport system (ETS) complexes in intact liver mitochondria isolated from 13-lined ground squirrels (Ictidomys tridecemlineatus) sampled during torpor and IBE to investigate potential sites of this reversible metabolic suppression. Flux through complexes I–IV and II–IV was suppressed by 40 and 60 %, respectively, in torpor, while flux through complexes III–IV and IV did not differ between torpor and IBE. We also measured maximal enzyme activity of ETS enzymes in homogenized isolated mitochondria and whole liver tissue. In isolated mitochondria, activities of complexes I and II were significantly lower in torpor relative to IBE, but complexes III, IV, and V did not differ. In liver tissue, only activity of complex II was suppressed during torpor relative to IBE. Despite the significant differences in both ETS flux and maximal activity, the protein content of complexes I and II did not differ between torpor and IBE. These results suggest that the rapid, reversible suppression of mitochondrial metabolism is due to regulatory changes, perhaps by post-translational modification during entrance into a torpor bout, and not changes in ETS protein content.

Keywords

Mitochondria Oxidative phosphorylation Metabolic suppression Mitochondrial respiration 

Supplementary material

360_2016_1022_MOESM1_ESM.pdf (71 kb)
Supplementary material 1 (PDF 71 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Katherine E. Mathers
    • 1
  • Sarah V. McFarlane
    • 1
  • Lin Zhao
    • 2
  • James F. Staples
    • 1
  1. 1.Department of BiologyUniversity of Western OntarioLondonCanada
  2. 2.Department of Physiology and PharmacologyUniversity of Western OntarioLondonCanada