Hyperbaric oxygen therapy protects the liver from apoptosis caused by ischemia-reperfusion injury in rats

Purpose: The present paper aimed to investigate the role of hyperbaric oxygen treatment (HBO) and the apoptosis in rat liver ischemia‐reperfusion injury (IRI). Methods: Thirty‐seven male Wistar rats were subjected to 30 minutes of hepatic ischemia and 30 minutes of reperfusion and randomly distributed into six groups: G‐I/R (n = 8), control without HBO; G‐HBO/I (n = 8), HBO only during the ischemia period; G‐HBO/R (n = 8), HBO only during the reperfusion period; G‐HBO‐I/R (n = 8), HBO during both the ischemia and reperfusion periods; G‐Sh (n = 3), HBO without ischemia or reperfusion as sham group; G‐C (n = 2) for control of current apoptosis expression on the normal liver tissue. HBO was carried out using a transparent, cylindrical acrylic chamber with a pressure of 2.0 ATA. Hepatic samples were stained for caspase‐3 cleavage. Results: Apoptotic cells were identified in all groups. In the hepatic specimens of animals HBO‐treated during ischemia (GHBO‐I), there was a significant decrease (P < 0.001) in the number of cells undergoing apoptosis (1.62 ± 0.91). The apoptotic index showed no significant difference in the animals HBO‐treated during ischemia/reperfusion (5.75 ± 1.28) compared with the G‐I/R (3.5 ± 0.75), which had no HBO treatment. The apoptosis index (11.25 ± 1.90) was significantly higher (P < 0.01) in HBO‐treated animals during the reperfusion period when compared with any of the other groups. Conclusion: A favorable effect was obtained when hyperbaric oxygen was administered early during ischemia. The hyperbaric oxygen in later periods of reperfusion was associated with a more severe apoptosis index. © 2009 Wiley‐Liss, Inc. Microsurgery 2009.