M. Dorigatti et al., EFFECTS OF HYPOXIA ON ENERGY-METABOLISM IN GOLDFISH HEPATOCYTES, Comparative biochemistry and physiology. B. Comparative biochemistry, 117(1), 1997, pp. 151-158
The present study addresses the question whether long-term acclimation
to hypoxia of the whole animal is accompanied by a chronic re-organiz
ation of cellular function and metabolism To this end, long- and short
-term effects of hypoxia on energy metabolism were studied in hepatocy
tes isolated from goldfish acclimated to normoxia or hypoxia (10% air
saturation). Aerobic (oxygen consumption) and anaerobic (lactate produ
ction under chemical anoxia) ATP turnover was not affected by acclimat
ion to hypoxia. The initial ATP content, a crude measure of energy sta
tus, was elevated in hypoxia-acclimated cells compared with normoxic c
ontrols but returned to control levels within 3 hr of normoxic exposur
e. Na+ pump activity and the rate of protein synthesis were estimated
from inhibitor sensitive rates of oxygen consumption. Neither of these
two major ATP consumers of the cell was significantly altered by hypo
xia acclimation, although Na+ pump activity showed a tendency to be el
evated in the acclimated cells. During exposure to chemical anoxia, a
pronounced decrease of lactate production was observed in hepatocytes
that may have been related to metabolic acidosis. The decrease of anae
robic energy output was not accompanied by a decrease of cellular [ATP
] and is therefore believed to reflect metabolic depression. The anaer
obic energy metabolism of goldfish hepatocytes relies on ample glycoge
n reserves and does not involve ethanol formation as a way to minimize
acidotic load. (C) 1997 Elsevier Science Inc.