RESUMO
Objective To investigate the signal mechanism of protein kinase C alpha(PKC-α)participated in enhanced expression of type Ⅰ inositol 1,4,5-trisphophate receptors (IP3 RI) induced by tumor necrosis factor alpha(TNFα),in order to delineate the mechanisms of decreased glomerular filtration rate (GFR) in hepatorenal syndrome caused by TNFα.Methods The glomerular mesangial cells (GMCs)line from rats was chosen as experimental material.GMCs were divided into control (D),TNFα-2 h,TNFα-4 h,TNFα-8 h,and TNFα-24 h groups.Moreover,another two groups were sanflngol-8h (S),TNFα + Sanfingol-8h(TS)groups.The effect of TNFα on the expression of IP3RI was detected by immunocytochemical staining,Western blotting,teal time-polymerase chain reaction (PCR) assays.Results Immunocytochemical staining demonstrated that IP3 RI was mainly distributed in cytoplasm of GMCs.Enhanced positive staining was determined in all TNFα-treated groups,especially in TNFα-8 h group.Western blotting demonstrated that the expression of IP3RI protein was significantly higher in TNFα-4 h,TNFα-8h and TNFα-24 h groups than control group(4 h:1.82 ± 0.63 ; 8 h:2.95 ± 0.66 ; 24 h:2.48 ± 0.72 ; D:1 ±0.02 ; F =9.24,P ＜ 0.05).The expression of IP3 RI protein was the highest in TNFα-8 h and TNFα-24 h groups(P ＜0.05).No difference was found among S,TS,and control groups(S:1.39 ±0.65; TS:1.35± 0.37 ; P ＞ 0.05).Real time-PCR found the expression of IP3 RImRNA was significantly higher in all TNFα-treated groups than control group(2 h:3.35 ± 1.97; 4 h:3.16 ± 1.35; 8 h:3.70 ± 1.76; 24 h:4.49±1.70; D:1 ±0.01; F =6.167,P ＜0.05).No difference was found among all TNFα-treated groups(P ＞0.05).No difference was found among S,TS,and control groups(S:1.53 ±0.79; TS:1.32 ± 0.38 ; P ＞ 0.05).Conclusions IP3 RI was mainly distributed in cytoplasm of GMCs.TNFa could enhance the expression of IP3 RI protein and IP3 RI mRNA,which could be blocked by sanfingol,a PKCα inhibitor.It might be an important signal in the mechanisms of GFR decrease caused by TNFα in hepatorenal syndrome.