Nilsson G E, Routley M H, Renshaw G M
Department of Biology, University of Oslo, Norway.
Proc Biol Sci. 2000 Jul 7;267(1450):1335-9. doi: 10.1098/rspb.2000.1147.
Elasmobranch fishes have long been noted for having unusually large brains for ectotherms, and therefore may be exceptions to the rule that vertebrates in general devote less than 8% of their resting metabolic rate to the central nervous system. The brain mass of sharks, skates and rays is often several times larger than that of teleost fishes of the same size. Still, the underlying reasons for this have remained unclear. Ion pumping by the Na+/K+-ATPase is the single most energy consuming process in the brain. In this study, Na+/K+-ATPase activity was measured in the brain of four species of elasmobranchs and 11 species of teleosts. While the average brain mass of the elasmobranchs examined was approximately three times that of the teleosts, the mean specific Na+/K+-ATPase activity was only about one-third of that of the teleosts. Thus, the total brain Na+/K+-ATPase activity was similar in elasmobranchs and teleosts. This suggests that the large brain size of elasmobranchs is at least partly related to a low mass-specific rate of brain energy use.
长期以来，人们一直注意到，软骨鱼类作为变温动物，其大脑异常大，因此可能是一般脊椎动物将不到8%的静息代谢率用于中枢神经系统这一规则的例外。鲨鱼、鳐鱼和魟鱼的脑质量通常是同等大小硬骨鱼类的几倍。然而，其背后的原因仍不清楚。钠钾ATP酶的离子泵浦是大脑中最耗能的单一过程。在这项研究中，测量了四种软骨鱼类和11种硬骨鱼类大脑中的钠钾ATP酶活性。虽然所检测的软骨鱼类的平均脑质量约为硬骨鱼类的三倍，但其钠钾ATP酶的平均比活性仅约为硬骨鱼类的三分之一。因此，软骨鱼类和硬骨鱼类大脑中钠钾ATP酶的总活性相似。这表明，软骨鱼类大脑体积大至少部分与大脑能量利用的低质量比速率有关。
