Effect of advanced glycosylation end products on activity of protein kinase C in human peripheral blood mononuclear cells

Objectives To investigate the effect of advanced glycosylation end products (AGEs) on the activity of protein kinase C (PKC) in human peripheral blood mononuclear cells (PBMC) and to observe whether aminoguanidine (AG) can influence the effect of AGEs. Methods After PBMC were isolated from human peripheral blood and incubated with different concentrations of AGEs-BSA for various periods, total PKC activity in PBMC was determined by measuring the incorporation of P-32 from [gamma-P-32] ATP into a special substrate using Promega PKC assay kit. Results AGEs-BSA increased the total PKC activity in PBMC from 83.43 +/- 6.57 pmol/min/mg protein to 116.8 +/- 13.82 pmol/min/mg protein with a peak at 15 min. AGEs-BSA also increased the total PKC activity in a concentration-dependent manner from 83.1 +/- 6.4 pmol/min/mg protein (control) to 119.1 +/- 13.3 pmol/min/mg protein (control vs AGEs-BSA 400 mg/L, P < 0.01). Furthermore, AGEs-BSA induced an elevation of PKC activity in a glycosylating time-related manner, from 80.9 +/- 8.2 (control) to 118.3 +/- 11.5 pmol/min/mg protein (glycosylation for 12 wk, P < 0.01). The total PKC activity stimulated by AGEs-BSA pretreated with AG (100, 200 mg/L) was markedly lower than that of AGEs-BSA group not pretreated with AG (P < 0.05, P < 0.01). Conclusions AGEs-BSA increased the total PKC activity in PBMC in a concentration and incubation time dependent manner. The ability of AGEs-BSA to stimulate PKC activity was markedly decreased by pretreatment of AGEs-BSA with AG.