Effect of carbon dioxide pneumoperitoneum on the expression and activity of arginase in rats

Abstract

Oxidative stress during carbon dioxide (CO2) pneumoperitoneum (PP) is reported to be associated with decreased bioavailability of nitric oxide (NO). However, the changes in endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS) and arginase during different intraabdominal pressures (IAP) of CO2 PP have not been elucidated.Thirty male Sprague-Dawley rats were randomized into three groups. After induction of anesthesia, the abdominal cavity of the rats of group IAP-10 and IAP-20 were insufflated with CO2 at pressures of 10 mmHg and 20 mmHg, respectively for 2 hours, while rats of group IAP-0 were not insufflated. After desufflation, plasma nitrite levels were measured while protein expression levels and activity of eNOS, iNOS, arginase I (Arg I) and arginase II (Arg II) were analyzed with aorta tissue samples. Tissue malondialdehyde (MDA) levels were also measured.Plasma nitrite levels and the expression of eNOS were significantly suppressed in groups IAP-10 and IAP-20 compared to group IAP-0. iNOS expression was found to be comparable between the three groups. Arg I and Arg II expression was significantly increased in groups IAP-10 and IAP-20 compared to group IAP-0. eNOS activity was significantly reduced in groups IAP-10 and IAP-20 compared to group IAP-0. Arginase activity was significantly increased in group IAP-20 compared to groups IAP-0 and IAP-10. MDA levels were also significantly increased in group IAP-20 compared to groups IAP-0 and IAP-10.eNOS expression and activity decreases during CO2 PP, which leads to a decrease in NO bioavailability and increased oxidative stress. Arginase expression and activity is increased during CO2 PP, which seems to act reciprocally with the NO system.