Effect of high glucose on renin-angiotensin system in rat glomerular endothelial cells and its associated mechanism / 中华肾脏病杂志

ABSTRACT

Objective To explore the effect of high glucose on the renin-angiotensin system (RAS) in rat glomerular endothelial cells and its probable mechanism.Methods Rat glomerular endothelial cells were stimulated by culture medium containing 5 mmol/L or 30 mmol/L glucose (with or without pre-treatment of captopril and chymostatin) for 12 h,24 h,48 h,72 h.ELISA,real-time PCR,Western blotting and confocal immunofluorescence microscopy were employed to examine the followsthe angiotensin Ⅱ (Ang Ⅱ ) concentration in cell lysate and the culture medium; the mRNA levels of angiotensinogen and renin; the protein levels of angiotensin Ⅱtype 1 receptor (AT1R),angiotensin Ⅱ type 2 receptor (AT2R),renin and angiotensinogen in cell lysate; localization of intracellular AT1R,AT2R and renin.Results Exposure to high glucose for only 12 h or 72 h resulted in a significant increase of Ang Ⅱ levels in the culture medium compared with control cells (P＜0.05),but only exposure to high glucose for 72 h resulted in a significant increase of Ang Ⅱ levels in the cell lysate compared with control cells (P＜0.05).However,exposure to high glucose for 24 h or 48 h had no effects on Ang Ⅱ levels in the cell lysate or culture medium.The captopril and chymostatin were able to antagonize high glucose induced Ang Ⅱ generation when exposure time was 72 h but not 12 h.Exposure to high glucoseincreased the mRNA level of angiotensinogen,but reduced the level of renin mRNA,meanwhile angiotensinogen protein increased,and AT1 protein reduced,but protein levels of AT2R and renin were unchanged.However,the transformation of AT2R from the cell nucleus to cytoplasm was observed.Conclusions High glucose can activate the local renin-angiotensin system in rat glomerular endothelial cells,and the probable mechanism may contribute to ACE and non-ACE pathways.The effects of high glucose on glomerular endothelial cells may also involve in the substrate and receptors of Ang Ⅱ.