Chronic hypoxia and developmental regulation of cytochrome c expression in rats.
OBJECTIVE
To test the hypothesis that chronic hypoxia upregulates cytochrome c expression in heart, brain, and liver of fetal and maternal rats.


METHODS
Time-dated pregnant Sprague-Dawley rats were divided into normoxic and hypoxic (48 hours of 10.5% oxygen from days 19 to 21) groups, and were killed on day 21. Tissue levels of cytochrome c in heart, brain, and liver were determined by using monoclonal antiserum for cytochrome c.


RESULTS
Chronic hypoxia caused a decrease in fetal body weight (5.3 +/- 0.1 to 4.7 +/- 0.1 g) and an increase in heart/body weight ratio (0.0048 +/- 0.0001 to 0.0061 +/- 0.0002). Cytochrome c levels were 4-, 2.6-, and 13-fold higher in heart, liver, and brain, respectively, of the mother than of the fetus. Chronic hypoxia did not change cytochrome c levels in maternal tissues but caused a 70% increase and 54% decrease in cytochrome c levels in the fetal heart and liver, respectively. No difference was observed in the fetal brain.


CONCLUSIONS
The results suggest that expression of cytochrome c is tissue specific and developmentally regulated. Chronic hypoxia showed differential regulation of cytochrome c levels both developmentally and tissue specifically. The increased sensitivity of cytochrome c in fetal tissue to chronic hypoxia is likely to represent a fetal adaptive mechanism to the stress of chronic hypoxia.
Xiao
D
D
Center for Perinatal Biology, Department of Pharmacology, Loma Linda University School of Medicine, Loma Linda, California 92350, USA.
Ducsay
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CA
Zhang
L
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D000818:Animals; D001921:Brain / Q000196:embryology / Q000201:enzymology; D003574:Cytochrome c Group / Q000032:analysis*; D005260:Female; D005311:Fetal Hypoxia / Q000201:enzymology*; D020567:Fetal Weight; D005865:Gestational Age; D006321:Heart / Q000196:embryology; D008099:Liver / Q000196:embryology / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D009929:Organ Size; D010100:Oxygen / Q000008:administration & dosage; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D003574:Cytochrome c Group; D010100:Oxygen