Effect Of Adrenomedullin On Tubular Cell Apoptosis Induced By Renal Ischemia Reperfusion Injury And Its Mechanisms

Objective To investigate the effect of adrenomedullin(AM) on tubular cell apoptosis induced by renal ischemia reperfusion injury and its mechanisms.Methods(1)Wistar rats were randomly divided into four groups: control group, IRI group, empty plasmid group and AM group. One week after removing of right kidney, eukaryotic expression vector encoding rat AM gene was transfect into the left kidney using an ultrasound-microbubble mediated system. The transfer efficiency were detected by immunohistochemical method after one week. Renal IRI model induced by clamping left renal arteries for 45 minutes followed by reperfusion for 24 hours.(2)Tubular cell apoptosis was detected by TUNEL assay.(3)Bcl-2, Bax and Fas expressions were examined by RT-PCR.(4)The expressions of caspase-3,caspase-8 and caspase-9 were determined by Western bolt analysis.Results(1)transfer efficiency:The expression of AM in AM group was significantly up-regulate than empty plasmid group.(2)Compared with control group,the apoptosis rate of renal tubular cell in IRI group was significantly higher (p<0.05).The expressions of Bax, Bcl-2, Fas, caspase-3, caspase-8 and caspase-9 were also significantly increased (p<0.05).Bax/Bcl-2 was increased (p<0.05).(3)Compared with IRI group, AM pretreatment significantly decreased the apoptosis rate of renal tubular cell. AM inhibited the up-regulation of Bax, Fas, caspase-3,caspase-8 and caspase-9,while promoted the up-regulation of Bcl-2 (p<0.05). Bax/Bcl-2 was decreased (p<0.05).(4)The above indexes had no differences between empty plasmid group and IRI group (p<0.05).ConclusionsAM can reduce tubular apoptosis induced by renal IRI, which is achieved, at least partly, by inhibiting caspase-dependent intrinsic and extrinsic pathways. Objective The ischemia/reperfusion injury (IRI) models of rat singal renal,which were transfected the eukaryotic expression vector of rat IMD,were established to simulate IRI in vivo,to investigate the effect of intermedin on the expressions of angiogenesis-related genes induced by renal ischemia reperfusion injury.Methods(1)Wistar rats were randomly divided into four groups: control group, IRI group, empty plasmid group and IMD group. control group:One week after removing of right kidney, blunt separate left renal artery but not clamp; IRI group:clamping left renal arteries for 45 minutes; empty plasmid group and IMD group:eukaryotic expression vector encoding rat IMD gene or empty plasmid was transfect into the left kidney using an ultrasound-microbubble mediated system.Renal IRI model induced by clamping left renal arteries for 45 minutes followed by reperfusion for 1d,2d,3d,4d,7d and14d.(2)The mRNA expressions of HIF-1a,VEGF and Tie-2 were examined by RT-PCR. (3)The protein expression of VEGF were examined by Western bolt analysis. (4)The protein expression of HIF-1a and Tie-2 were determined by ELISA.Results(1)Compared with control group,an increase in HIF-1a,VEGF and Tie-2 was observed in the IRI group at 1d,2d and 3d(p<0.05).The expression of HIF-1a was with a maximum at 1d(p<0.05),while VEGF and Tie-2 at 2d(p<0.05),followed by a decrease that wsa similar to control levels at 4d(p>0.05).(2)Compared with the IRI group, the expressions of HIF-1a,VEGF and Tie-2 of IMD group all reached the peak at 1d(p<0.05),maintained at 2-4d(p<0.05),followed by a decrease was similar to control levels at 7d(p>0.05).(3)The above indexes had no differences between empty plasmid group and IRI group (p>0.05).Conclusions IMD can improve and prolong the expressions of angiogenesis-related genes(HIF-1a,VEGF and Tie-2) induced by renal ischemia reperfusion injury,witch may take part in the renal recovery.