Cold preservation-warm reoxygenation increases hepatocyte steady-state Ca(2+) and response to Ca(2+)-mobilizing agonist.
Although the role of Ca(2+) in liver transplantation injury has been the object of several studies, direct evidence for alterations in intracellular Ca(2+) homeostasis after cold preservation-warm reoxygenation (CP/WR) has never been presented. We thus investigated the effects of CP/WR on steady-state Ca(2+) and responses to a Ca(2+)-mobilizing agonist. Isolated rat hepatocytes were suspended in University of Wisconsin solution, stored at 4 degrees C for 0, 24, and 48 h, and reoxygenated at 37 degrees C for 1 h. Cytosolic Ca(2+) was measured in single cells by digitized fluorescence videomicroscopy. CP/WR caused a significant increase in steady-state cytosolic Ca(2+), which was inversely proportional to cell viability. Pretreatment of hepatocytes with an agent that protects mitochondrial function attenuated the increase in steady-state cytosolic Ca(2+) and improved hepatocyte viability. Ca(2+) responses to the purinergic agonist ATP also increased significantly as a function of cold storage time. This increase was related to an increase in the size of inositol 1,4,5-trisphosphate-sensitive Ca(2+) stores and subsequent capacitative Ca(2+) entry. Thus CP/WR significantly perturbs steady-state hepatocellular Ca(2+) and responses to Ca(2+)-mobilizing agonists, which may contribute to hepatocyte metabolic dysfunction observed after CP/WR.
Elimadi
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Membrane Transport Research Group and Department of Pharmacology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada H3C 3J7. elimadia@magellan.umontreal.ca
Haddad
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D019797:3-Iodobenzylguanidine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003080:Cold Temperature; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature
D019797:3-Iodobenzylguanidine; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D010100:Oxygen; D002118:Calcium