Effects of different doses of dexmedetomidine on myocardial injury induced by renal ischemia-reperfusion in rats / 医学研究生学报

ABSTRACT

Objective Renal ischemia-reperfusion may cause myocardial injury and dexmedetomidine ( DEX)is a new alpha-2 adrenergic agonist which has the effects of antisympathia , sedation and analgesia.The article was to observe the effects of different doses of dexmedetomidine on myocardial injury induced by renal ischemia -reperfusion(I/R) in Rats. Methods 40 male Wistar rats were randomized into 5 groups(n=8 each)using a random number table sham operation group(isolation of bilateral renal pedicles without ligation), I/R group (3 hours′reperfusion 120 minutes after the right nephrectomy and the ligation of left renal artery ), DEX low dose group, DEX middle dose group and DEX high dose group (DEX 25, 50, 100 μg/kg were respectively injected intraperitone-ally in rats of the three groups plus 3 hours′reperfusion after 120 minutes′ischemia ) .Blood samples were collected at 3 hours′reper-fusion to determine serum creatinine(Cr) and blood urea nitrogen(BUN) concentrations.Kidney and myocardial specimens were ex-tracted for microscopic examination and IL-10,TNF-αcontent were detected by ELISA. Results In sham operation group, renal structure was normal.In I/R group, a great amount of erythrocyte infiltration and interstitial infiltrating inflammatory cells were found in glomerulus and a lot of exfoliative cells were found in renal tubules .In DEX low dose group , erythrocyte infiltration and interstitial infiltrating inflammatory cells were found in glomerulus and a few exfoliative cells were found in renal tubules .In DEX middle dose group, erythrocyte infiltration and interstitial infiltrating inflammatory cells were found in partial glomerulus and a few exfoliative cells were found in renal tubules .In DEX high dose group , erythrocyte infiltration and interstitial infiltrating inflammatory cells in partial glomerulus were found and rare exfoliative cells were found in renal tubules .In sham operation group , cardiomyocytes were arranged in perfect order and normal structure , and chromatins and cytoplasms were in uniform distribution .In I/R group, edema and spongiform were obvious in cardiomyocytes , and focal coagulative necrosis was observed along with a great amount of infiltrating inflammatory cells and rare flaky bleeding .In DEX low dose group , edema and spongiform were found in cardiomyocytes , and focal coagulative necrosis was observed along with a great amount of infiltrating inflammatory cells and rare flaky bleeding .In DEX middle dose group , edema was found in cardiomyocytes , and mini focal coagulative necrosis was observed along with a small amount of infiltrating inflammatory cells.In DEX high dose group , edema was found in cardiomyocytes along with a small amount of infiltrating inflammatory cells .Com-pared with sham operation group , Cr, BUN concentrations in serum and IL-10,TNF-αcontents in kidney tissue and myocardium signif-icantly increased in I/R group, low dose group, middle dose group and high dose group(P<0.05).Compared with I/R group, IL-10 contents kidney tissue and myocardium significantly increased in small dose group (P<0.05).Cr ([167.11 ±18.81, 135.46 ± 9.80, 114.29 ±12.50, 100.15 ±8.81]μmol/L), BUN ([13.42 ±1.25, 11.73 ±1.15, 10.27 ±0.78, 9.28 ±0.52] mmol/L) concentrations in serum and TNF-αcontents in kidney tissue ([578.45 ±30.59, 530.76 ±20.59, 482.23 ±27.12, 423.14 ± 21.16]ng/L) and myocardium ([565.00 ±37.66, 517.82 ±36.89, 469.99 ±32.43, 407.41 ±23.77] ng/L) significantly de-creased in a dose-dependent manner in low , middle and high groups (P<0.05).Microscopic examination showed that the pathological changes of both kidney tissue and myocardium were significantly attenuated in low , middle and high dose group . Conclusion Dexmedetomidine can allenuate myocardial tissue injury induced by renal ischemia -reperfusion in a dose-dependent manner in rats and its mechanism may be involved with the inhibition of inflammatory factors .