PBOSSER 



either no effect or a very slight compensation and goldfish liver has 

 no such excess of cytochrome oxidase as rat liver (Murphy, 1961). 

 Catalase showed no change ( Carassius gill, Ekberg, 1961) or an in- 

 verse or t)T)e 5 acclimation (eel liver, Precht, 1951). No differences 

 between warm- and cold- acclimated goldfish were found for DPNH 

 reductase and TPNH cytochrome reductase (Murphy, 1961). Wide 

 variability in P/O ratios led to equivocal results (Kanungo and Pros- 

 ser, 1959a; Murphy, 1961). 



The enzymes of the hexose monophosphate shunt show very low 

 activity in fish, and their importance is doubtful (Brown, 1960). For 

 example, the activity of glucose- 6- phosphate dehydrogenase in gold- 

 fish liver is only 3% of that in rat liver (Murphy, 1961). This enzyme 

 showed no compensation in crucian carp gill (Ekberg, 1961) and an 

 inverse (type 5) acclimation in goldfish liver (Murphy, 1961). Another 

 enzyme of the shunt, 6- phospho- gluconic dehydrogenase, showed a 

 large compensation in crucian carp gills, but no change in goldfish 

 liver homogenates. The suggestion (Kanungo and Prosser, 1959b) 

 that there might be increased use of the monophosphate shunt in the 

 cold seems invalid. 



The most important metabolic changes in acclimation to cold 

 seem to be in glycolytic enzymes. Sluggish fish such as carp are said 

 to survive anaerobically in the cold (Blazka, 1958). Active fish such 

 as the Kamloops trout show an increase in lactic acid concentration 

 in muscle of as much as 4 l/2 times in 9 minutes of exercise and 

 elevated lactic acidpersisted for several hours post- exercise (Black 

 et al., 1960, 1961). Blood lactate in unexercised trout and salmon is 

 high in comparison with mammals and may rise as much as 6 to 10 

 fold after exercise (Black et al., 1960). Pyruvate follows the same 

 time course as lactate. A trout accumulates lactic acid and pays off 

 an C debt (Black et al., 1960); a crucian carp does not accumulate 

 lactate but increases its CO excretion (Blazka, 1958). It appears 

 that fish rely considerably on glycolytic metabolism. Lactic dehy- 

 drogenase activity is high in goldfish liver, and it shows some tem- 

 perature compensation (Murphy, 1961). Total acid production by cru- 

 cian carp gills was elevated in cold-acclimation, but the CO pro- 

 duction was not (Ekberg, 1961). Aldolase was markedly increased in 

 carp gills by cold acclimation (Ekberg, 1961). lodoacetate sensitivity 

 of goldfish gills was less in the cold. It appears that the most 



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