Glutathione and Nitric Oxide Concentrations in Glutamine-Infused Rabbits with Intestinal Ischaemia/Reperfusion

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Abstract
Intestinal ischaemia/reperfusion causes formation of reactive oxygen intermediates which lead to mucosal cell injury. Glutathione, a scavenger of reactive oxygen intermediates, protects tissues from reactive oxygen intermediate-mediated cell injury. Nitric oxide is a lipophilic gas and its synthesis is stimulated by ischaemic conditions. In this experimental study, we aimed to investigate the role of i. v. L-glutamine infusion on mucosal tissue glutathione and serum nitric oxide concentrations in intestinal ischaemia/reperfusion. External jugular vein of albino rabbits was cannulated with catheter and infused with normal saline at 4 ml/h. After 3 days, they were randomly divided into two main groups. Group 1 (n = 30) received i. v. normal saline alone, group 2 (n = 30) received normal saline + 205 mmol/l glutamine at 4 ml/h for 24 hours. Next, mucosal glutathione and serum nitric oxide concentrations were measured after 0, 30, 60 min of ischaemia/60 min of reperfusion. Basal glutathione concentrations were similar in normal saline alone and normal saline + 205 mmol/l glutamine infusion groups (p > 0.05). At 30 and 60 min of ischaemia/60 min of reperfusion, glutathione concentrations were significantly lower in normal saline-infused rabbits compared to the normal saline + 205 mmol/l glutamine-infused rabbits (p < 0.05). In addition, serum nitric oxide concentrations were found to be significantly increased in rabbits 30 and 60 min after ischaemia/reperfusion when compared to mean basal nitric oxide concentrations obtained from control animals. However, the normal saline + 205 mmol/l glutamine group had lower serum nitric oxide concentrations than did the normal saline alone group. In conclusion, this study revealed that intestinal mucosal glutathione concentrations were significantly higher in glutamine-receiving rabbits than in non-receiving ones. Additionally, it was shown that nitric oxide concentrations increased in ischaemia both in normal saline alone and normal saline + 205 mmol/l glutamine receiving groups, while this increase in nitric oxide was more prominent in the normal saline alone group (p < 0.01). These findings show that glutamine supplementation may protect the small intestine from ischaemia/reperfusion injury and may play a regulatory role in the biosynthesis of nitric oxide.