ABSTRACT
Objective To investigate the effect of tumor necrosis factor-α (TNF-α) on intracellular calcium concentration ([Ca2 +] i) and the contraction of glomerular mesangial cells (GMCs),and prove that hypercontractility of GMCs induced by TNF-α in hepatorenal syndrome(HRS) was connected with inositol 1,4,5-trisphophate receptors (IP3Rs).Methods GMCs were divided into TNF-α-treated 0 h,4h,and 24 h groups.Another 3 groups were blocked by 2-APB.The effect of TNF-α on [Ca2 +] i was identified and observed whether it could be blocked by 2-APB.Contraction of GMCs was determined by accessing the surface area of cells before and after contraction.Results TNF-α significantly increased ET-induced calcium release,in that we found higher [Ca2 +] i after stimulated by ET in TNF-α-treated 4 h group and 24 h group[4 h:(648.08 ±267.11) nmol/L; 24 h:(879.30 ±-260.29) nmol/L; 0 h:(619.93 ±258.94)nmol/L,F =5.486,4 h vs 0 h:P ＜ 0.05 ; 24 h vs 0 h:P ＜ 0.05 ;24 h vs 4 h:P ＞ 0.05].This phenomenon can be totally blocked by 2-APB in all groups.The change in planar surface area in response to ET was slightly in control cells but significantly enhanced in TNF-α-treated cells [4 h:(2198 ± 340)μm2; 24h:(2260±553)μm2; 0 h:(2436±474)μm2,F =4.001,4 h vs0 h:P ＜0.05; 24 h vs0 h:P ＜0.05;24 h vs 4 h:P ＞ 0.05].Conclusion TNF-α can enhance ET-induced sarcoplasmic reticulum Ca2 + release and increase the contractile responses of GMCs to ET,which is associated with IP3Rs.TNF-α is responsible for hyperconstractility of glomeruli in HRS.