Alterations of Na+,K(+)-ATPase activity after hypoxia and reoxygenation in the perfused rat liver: an electron microscopic cytochemical study.
OBJECTIVE
Using the cerium technique for ultrastructural cytochemical studies, Na+,K(+)-ATPase activity was investigated in hypoxic and reoxygenated rat liver.


METHODS
In the control group, the livers were perfused with oxygenated hemoglobin-free Krebs-Henseleit buffer for 1 h. For hypoxia (60 min), the flow rate of the perfusate was decreased and oxygen was replaced by nitrogen. For reoxygenation, the liver was reperfused under oxygenated conditions for 5 min after 60 min of hypoxia.


RESULTS
In control livers, a strong Na+,K(+)-ATPase activity was detected at the basolateral membrane of hepatocytes while the apical membrane forming the bile canaliculi did not display any staining. In hypoxic livers, Na+,K(+)-ATPase activity had ceased in the plasma membrane of hepatocytes. In reoxygenated livers, Na+,K(+)-ATPase was rapidly reactivated in the basolateral hepatic membrane. The membrane of blebs generated during the hypoxic phase also showed enzyme activity. In addition, a striking accumulation of reaction product could be observed in about 10% of the apical membranes lining the bile canaliculi.


CONCLUSIONS
The results indicate a plasticity of the Na+,K(+)-ATPase in hypoxic and reoxygenated rat liver.
Angermüller
S
S
Department of Anatomy and Cell Biology II, University of Heidelberg, Germany.
Schunk
M
M
Kusterer
K
K
Konrad
T
T
Usadel
K H
KH
D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D005260:Female; D006651:Histocytochemistry; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D008854:Microscopy, Electron; D010100:Oxygen / Q000627:therapeutic use*; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000254:Sodium-Potassium-Exchanging ATPase; D010100:Oxygen