Turtles and rats: a biochemical comparison of anoxia-tolerant and anoxia-sensitive brains.
When temperature differences are taken into account, turtle brains use glucose at one-sixth the rate reported in rat brains. Na+-K+-ATPase activities are 2- to 2.5-fold higher in rat than in turtle brains. Maximal activities of hexokinase and lactate dehydrogenase are similar, whereas citrate synthase activities are two- to threefold higher in rat than turtle brains at the respective biological temperatures. Voltage-dependent Ca2+ channel densities, when compared between the two species, showed no consistent pattern. These data, along with the threefold differences in density of voltage-dependent Na+ channels reported by Lutz et al., are consistent with the idea that lower rates of channel and pump-mediated Na+ and K+ fluxes result in lower rates of aerobic energy metabolism in turtle brains compared with rat brains.
Suarez
R K
RK
Department of Zoology, University of British Columbia, Vancouver, Canada.
Doll
C J
CJ
Buie
A E
AE
West
T G
TG
Funk
G D
GD
Hochachka
P W
PW
D000222:Adaptation, Physiological; D000818:Animals; D001921:Brain / Q000201:enzymology / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism / Q000502:physiology; D004594:Electrophysiology; D004734:Energy Metabolism; D005947:Glucose / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D051381:Rats / Q000378:metabolism*; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014426:Turtles / Q000378:metabolism*
D015220:Calcium Channels; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose