Characterization of mitochondrial respiratory chain energetics in the vestibular nucleus complex.
CONCLUSIONS
Despite having very high neuronal firing rates, the VNC does not have unusually high mitochondrial activity in vitro. This study is the first in which functionally active mitochondria from the hindbrain have been isolated and characterized.


OBJECTIVE
Neurons in the vestibular nucleus complex (VNC) have exceptionally high spontaneous firing rates. Neuronal mitochondria generate adenosine triphosphate critical for maintaining the membrane potentials required for axon firing. We therefore hypothesized a high rate of mitochondrial activity in the VNC.


METHODS
To test this hypothesis, we compared mitochondrial activity in the VNC with mitochondrial activity from another area of the hindbrain, the cerebellum. Mitochondrial respiratory activity was assessed by measuring oxidative phosphorylation and mitochondrial respiratory enzyme complex activity.


RESULTS
Assay results were not significantly different in the VNC compared to those obtained with the cerebellum or with rat brain mitochondria in previous studies.
Ashton
John C
JC
Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, University of Otago, Dunedin, New Zealand. john.ashton@stonebow.otaga.ac.nz
Khalessi
Amirala
A
Kapoor
Mohit
M
Clarkson
Andrew
A
Sammut
Ivan A
IA
Darlington
Cynthia L
CL
Smith
Paul F
PF
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology*; D042967:Electron Transport Complex I / Q000378:metabolism; D042963:Electron Transport Complex II / Q000378:metabolism; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010085:Oxidative Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D014726:Vestibular Nuclei / Q000502:physiology*
D000255:Adenosine Triphosphate; D042963:Electron Transport Complex II; D003576:Electron Transport Complex IV; D002950:Citrate (si)-Synthase; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III