Inhalation Of Low Concentrations Of Carbon Monoxide On Renal Ischemia-reperfusion Injury In Rats

Renal ischemia-reperfusion (IR) injury is most frequently encountered in traumatic stress,hemorrhagic shock,kidney and renal transplant patients transfer process. Prevention and curing IR injury play the key roles. Recent studies suggested the insult from Ischemia-Reperfusion was a multi-factorial injury involving post-ischemia inflammatory. Additionally, IR injury was induced by inflammatory mediators and active oxygen which freed by ischemic cells. Carbon monoxide (CO) has important functions under physiological and pathophysiological conditions. Recent studies suggested anti-inflammatory and anti-apoptotic effects. Our laboratories and others have demonstrated that the administration of exogenous carbon monoxide (CO) at low concentrations prevents multiple organ injury in a model of Ischemia-Reperfusion on right hind limb. Another reported that exogenous CO (volume fraction 0.05%) have a protective effect in renal transplantation. The above results show that, CO direct and indirect effects of renal IR injury in both prevention and treatment, and further the system of CO on renal IR injury and its laws, the treatment of these patients can provide new coping strategies.Objective: The objective of this study was to be adopted by renal artery occlusion and re-open method of reproduction of renal IR injury model, so that the model animals, inhalation of different concentrations (volume fraction in a safe range) of the CO, the observed indicators of renal function and pathological changes to of different concentrations of CO effect on renal IR injury.Methods: (1) Animal group: Thirty healthy Sprague-Dawley rats, male and female informal, weighing 250-300g, were selected and randomly divided into three groups: S (six rats), IR (six rats) and RC (eighteen rats). RC were divided into RC0.025, RC0.05 and RC0.075 concentration groups, each with the volume fraction of inhaled CO, respectively 0.025%, 0.05%, 0.075%. (2) Model copy: the anesthesia state, the exposure and free bilateral renal pedicle, using non-invasive vascular clip of their occlusion, 45 min later, remove the blood vessel clip the implementation of reperfusion, as obtained in rat model of renal IR. S group of simulated surgical procedure, but does not cause renal ischemia. (3)CO inhalation method: RC animals inhaled CO, animals placed in special containers, the pass into the air containing CO, medical, CO volume fraction of 0.025%, respectively, 0.05%, 0.075%. 1h before surgery and postoperative 6h continuously exposed to CO. S, IR group exposed to air, breathe freely. (4) Derived observations: IR, RC0.025, RC0.05 and RC0.075 group to the 6 h reperfusion time, S group at the corresponding point in time, in the depth of anesthesia, the right atrium through the blood of 5mL, put it aside, centrifuged and the supernatant sending automatic biochemical analyzer potassium (K+), creatinine (CRE), blood urea nitrogen (BUN) and other indicators of renal function, abdominal kidney were taken to do the following observation: right kidney color, texture and the seepage situation in general observation, photography; take the right kidney for determination of wet-dry weight ratio, using electronic analytical balance measuring wet weight, temperature incubator at 60°C electric drying 7 days until the water completely dry weight was measured after precipitation of , considered as wet-dry weight ratio; take the left kidney paraffin-embedded sections, HE staining, histopathological observations.Results: (1) The observation on the whole: S group, renal dull red color, good elasticity, no bleeding and exudation; IR group, kidney darker color, brown, marked swelling, flexibility is poor, within the renal cortex slice bleeding points; RC group, the color of kidney IR between S and between groups, the elastic touch better than the IR group, the cortical hemorrhage is lower than IR group decreased significantly. (2) The wet/dry weight ratio: IR group was the highest, S group was the lowest and RC group was in the middle. R Group> RC0.025 group> RC0.05 group> RC0.075 group> S group. IR group and compared with the other groups, there is significant difference (P<0.05). S group and compared with the other groups, there is significant difference (P<0.05). There was no significant difference between RC0.05 group and RC0.075 group (P>0.05). (3) Observed by HE staining: S group, glomerular and renal tubular epithelial cells, no swelling and degeneration, the cells were morphologically normal, the lumen size of the normal renal blood vessels can be seen within the gathered piles of red blood cells. IR group, tubular epithelial swelling and serious, widespread epithelial cell degeneration, necrosis, shedding, the lumen narrowed or closed, some become large lumen, the lumen containing necrotic cell aggregation of cells to form tube-type and large flocculant. Glomerular and retrobulbar capillary endothelial cell swelling, intravascular deposition of a large number of structural damage red blood cells and hemoglobin, renal interstitial congestion and bleeding obvious, accompanied by inflammatory cell infiltration. RC group, with the S group still showed abnormal performance, but the IR group compared with mild disease, especially in RC0.075 showed significantly improved. Some tubular epithelial cell swelling, detachment and degeneration and necrosis of cells, small, tubular shape, maintain a good lumen seen in the protein tube type and floc, necrosis cell aggregation of cells to form tube-type rare. (4) Serum test results: S group, serum K+, BUN, CRE value is the lowest, at a basic level within the normal reference range; IR group, serum K, BUN, CRE maximum value; RC of each group of serum K+, BUN, CRE value center. Statistically significant difference between the two groups were compared (P<0.05).Conclusion: The inhalation of exogenous CO can significantly reduce renal IR injury. When the concentration was in the safe range, the concentration of CO inhaled corresponded to its effect.