Journal of Comparative Physiology B

, Volume 181, Issue 5, pp 699–711

Mitochondrial respiration and succinate dehydrogenase are suppressed early during entrance into a hibernation bout, but membrane remodeling is only transient

  • Dillon Chung
  • Graham P. Lloyd
  • Raymond H. Thomas
  • Chrisopher G. Guglielmo
  • James F. Staples
Original Paper

DOI: 10.1007/s00360-010-0547-x

Cite this article as:
Chung, D., Lloyd, G.P., Thomas, R.H. et al. J Comp Physiol B (2011) 181: 699. doi:10.1007/s00360-010-0547-x

Abstract

We examined respiration and lipid composition of liver mitochondria purified from a hibernator (Ictidomys tridecemlineatus) in different stages of a torpor bout. Between interbout euthermia (body temperature, Tb, 37°C) and early entrance (Tb 30°C), state 3 and state 4 respirations, fueled by 6 mM succinate, fell by over 50%. Mitochondrial respiration did not decline any further in the late entrance and torpor stages (Tb 15 and 5°C, respectively). Succinate dehydrogenase (SDH) activity declined in a similar pattern as mitochondrial respiration, and there was a significant positive correlation between state 3 respiration and SDH activity. However, unlike during arousal from torpor, oxaloacetate was not a major factor in inhibition of SDH. Analysis of mitochondrial lipids showed little change in neutral lipids or phospholipid classes, except for a transient decrease in phosphatidylethanolamine content in early entrance. In the transition from interbout euthermia to early entrance, we found transient increases in some saturated phospholipid fatty acids (16:0, 18:0) and decreases in some unsaturates (18:2, 20:4). These changes resulted in transient increases in total saturates and the ratio of saturates to unsaturates, and transient decreases in total unsaturates, total polyunsaturates, total n-6, the ratio of monounsaturates to polyunsaturates, and unsaturation index. None of these changes persisted into late entrance or torpor, nor did they correlate with mitochondrial respiration. We conclude that mitochondrial metabolic suppression during entrance into a torpor bout occurs very early and is likely related to acute regulation of electron transport chain enzymes rather than changes in membrane phospholipid composition.

Keywords

Hibernation Entrance Mitochondria Succinate dehydrogenase Phospholipids 

Abbreviations

ETC

Electron transport chain

FA

Fatty acid

LPC

Lysophosphatidylcholine

\( M_{\rm O_2} \)

Whole-animal oxygen consumption

MUFA

Monounsaturated fatty acid

OAA

Oxaloacetate

PE

Phosphatidylethanolamine

PC

Phosphatidylcholine

PS

Phosphatidylserine

PUFA

Polyunsaturated fatty acid

SDH

Succinate dehydrogenase

Tb

Core body temperature

UI

Unsaturation index

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Dillon Chung
    • 1
  • Graham P. Lloyd
    • 1
  • Raymond H. Thomas
    • 1
  • Chrisopher G. Guglielmo
    • 1
  • James F. Staples
    • 1
  1. 1.Department of BiologyUniversity of Western OntarioLondonCanada