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Intermittent ischemia reduces warm hypoxia‐reoxygenation–induced JNK 1 /SAPK 1 activation and apoptosis in rat hepatocytes
Author(s) -
Crenesse Dominique,
Laurens Marina,
Gugenheim Jean,
Heurteaux Catherine,
Cursio Raffaele,
Rossi Bernard,
SchmidAlliana Annie
Publication year - 2001
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1053/jhep.2001.28709
Subject(s) - tunel assay , ischemia , apoptosis , alanine transaminase , aspartate transaminase , terminal deoxynucleotidyl transferase , hypoxia (environmental) , medicine , endocrinology , necrosis , biology , chemistry , biochemistry , enzyme , alkaline phosphatase , organic chemistry , oxygen
Abstract Prolonged liver ischemia followed by reperfusion (I/R) causes functional and structural damage to liver cells, resulting in necrosis and apoptosis. c‐jun N‐terminal kinase 1/stress‐activated protein kinase 1 (JNK 1 /SAPK 1 ) is activated during I/R and participates in the onset of the apoptosis program. Excessive blood loss during surgery can hinder postoperative recovery. Intermittent portal triad clamping (PTC) is better tolerated than prolonged continuous ischemia. This study was designed to demonstrate that intermittent ischemia could improve postischemic survival rates by a decrease of JNK 1 /SAPK 1 and caspase 3 activation, which were involved in the apoptosis process. Rats were subjected to intermittent 1‐hour ischemia (15‐minute ischemia/5‐minute reperfusion, 4 times), followed by 220‐minute reperfusion, or to continuous ischemia (1 hour), followed by 240‐minute reperfusion. Mortality rates were assessed on day 7. Serum aspartate transaminase (AST), alanine transaminase (ALT), and lactate deshydrogenase levels (LDH) were measured 6 hours after ischemia. This study was completed in primary cultured isolated rat hepatocytes, subjected to the same continuous or intermittent hypoxic conditions. The activation status of JNK 1 /SAPK 1 was evaluated by immunoprecipitation or Western blotting experiments. Apoptosis was assessed by measuring caspase activation and by terminal deoxynucleotidyl transferase–mediated dUTP biotin nick end labeling (TUNEL) reaction. Eighty percent of the intermittent‐ischemia group was alive 7 days after surgery and serum enzyme levels were significantly decreased. Intermittent hypoxia or ischemia did not lead to JNK 1 /SAPK 1 activation, but at least 3 hypoxia‐reoxygenation (H/R) sets were necessary to inhibit kinase activation. Consequently, caspase 3 activation and apoptosis were dramatically reduced. Intermittent ischemia is a powerful, protective way to reduce I/R damage of the liver, by reduction of JNK 1 /SAPK 1 activation associated with a down‐regulation of caspase 3 activity, which leads to inhibition of hepatocyte apoptosis.