Anaerobic and aerobic energy metabolism in brain and liver tissue from rainbow trout (Salmo gairdneri) and bullhead catfish (Ictalurus nebulosus)

Abstract

AbstractThis study tested the hypothesis that tissue from a fish species relatively resistant to anoxia would exhibit a reduced Pasteur effect, as has been shown for some other anoxia‐resistant animals. The extent to which temperature compensation occurs in glycolysis was also examined. The production of ATP by oxidative metabolism and glycolysis was partitioned in brain and liver tissue from rainbow trout (Salmo gairdneri), an anoxia‐sensitive species, and bullhead catfish (Ictalurus nebulosus), an anoxia‐resistant species. Measurements were made under normoxic and anoxic conditions and at different temperatures, using glucose as a substrate. Oxidative metabolism (estimated by oxygen consumption) and glycolysis (estimated by lactate accumulation) under normoxic conditions exhibited relatively good temperature compensation, compared with that of anoxic glycolysis. Exposure to anoxia caused a two‐ to threefold increase in glycolysis in brain tissue but not in liver (i.e., brain exhibited a Pasteur effect). At 5°C, the Pasteur effect was lost in both species. The findings do not support the hypothesis; instead, the catfish brain tissue actually had a slightly larger Pasteur effect than did the trout. Bullhead catfish brain tissue has approximately five times the glycogen concentration of the trout. Thus brain tissue of the catfish has both a somewhat greater anaerobic scope and a much larger anaerobic capacity than does the trout.