Protective effect of heat shock protein 70 and magnesium sulfate supplementation on renal ischemia reperfusion injury

To investigate whether there is a protective mechanism in exogenous magnesium ions supplement in renal ischemia reperfusion injury(IRI ), and to study the expression of heat shock protein 70 (HSP70) and HSP70-mRNA in the reperfusion injury.A total of 90 male Japanese white rabbits (1.8-2.0 kg) were divided into three groups: ischemia reperfusion group (I-R), MgSO4 pretreatment group and sham operation group. The right kidney was cut through median abdominal incision to make solitary kidney model. The left renal artery was blocked for 1 h in I-R group and MgSO? group. 2.5% MgSO? 1 mL/(kg×h) was given through ear vein before the artery was blocked and during the blockeage in the MgSO? group. the kidney cortex tissue was taken 1, 2, 4, 24, 48 and 72 h after reperfusion. Immunohistochemical examination was used to determine the HSP70 expression. A modified quantitative Real time-PCR was used to quantitate HSP70-mRNA in the three groups. Pathological examination was also used to confirm the results.Real time-PCR showed that HSP70-mRNA began to increase at the end of 1 h, and reached the peak at the end of 2 h in both I-R and MgSO? groups, but expression in I-R group which was remarkably higher than that in the MgSO? group at the end of 2 h and 4 h ( P<0.05). HSP70-mRNA levels decreased rapidly at the end of 24 h. In I-R group, moderate HSP70 expression could be seen in the proximal tubules during immunohistochemical examination after reperfusion for 24 h and 48 h. By contrast, there was weak HSP70 expression in the MgSO? group 24 h and negative 48 h after reperfusion. Epithelial shedding, border brush, inflammatory cell infiltration and protein casts were serious after 24 to 48 h reperfusion, while only slight tubular cell shedding and necrosis could be found in the MgSO? group at the matched time.Magnesium supplement can significantly relieve the renal ischemia reperfusion injury. It can inhibit the upregulated expression of HSP70 and HSP70-mRNA in vivo, which demonstrates that the expression of HSP70 is not necessary in the protective mechanism.PubMed04525-304