AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 5 1083-R1088, Copyright © 1989 by American Physiological Society

ARTICLES

Turtles and rats: a biochemical comparison of anoxia-tolerant and anoxia-sensitive brains

R. K. Suarez, C. J. Doll, A. E. Buie, T. G. West, G. D. Funk and P. W. Hochachka
Department of Zoology, University of British Columbia, Vancouver, Canada.

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.

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