Stimulation of p38 MAP kinase reduces acidosis and Na(+) overload in preconditioned hepatocytes.
Ischemic preconditioning has been shown to improve liver resistance to hypoxia/reperfusion damage. A signal pathway involving A(2A)-adenosine receptor, G(i)-proteins, protein kinase C and p38 MAP kinase is responsible for the development of hypoxic preconditioning in hepatocytes. However, the coupling of this signal pathway with the mechanisms responsible for cytoprotection is still unknown. We have observed that stimulation of A(2A)-adenosine receptors or of p38 MAPK by CGS21680 or anisomycin, respectively, appreciably reduced intracellular acidosis and Na(+) accumulation developing during hypoxia. These effects were reverted by p38 MAPK inhibitor SB203580 as well as by blocking vacuolar proton ATPase with bafilomycin A(1). SB203580 and bafilomycin A(1) also abolished the cytoprotective action exerted by both CGS21680 and anisomycin. We propose that the stimulation of p38 MAPK by preconditioning might increase hepatocyte resistance to hypoxia by activating proton extrusion through vacuolar proton ATPase, thus limiting Na(+) overload promoted by Na(+)-dependent acid buffering systems.
Department of Medical Sciences, University 'A. Avogagro' of East Piedmont, Via Solaroli 17, 28100, Novara, Italy.
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Carini
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Grazia De Cesaris
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Splendore
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Albano
D000138:Acidosis / Q000378:metabolism*; D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007424:Intracellular Fluid / Q000378:metabolism; D019194:Ischemic Preconditioning; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010627:Phenethylamines / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D017208:Rats, Wistar; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D025262:Vacuolar Proton-Translocating ATPases; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D010627:Phenethylamines; D011500:Protein Synthesis Inhibitors; D058906:Purinergic P1 Receptor Agonists; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D000841:Anisomycin; D012964:Sodium; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D000241:Adenosine