EFFECTS OF GLUCOSE AND SNK-860, AN ALDOSE REDUCTASE INHIBITOR, ON THEPOLYOL PATHWAY AND CHEMILUMINESCENCE RESPONSE OF HUMAN NEUTROPHILS IN-VITRO

An in vitro incubation study was conducted to investigate whether incr eased activity of the polyol pathway in human neutrophils under diabet ic conditions resulted in a decrease of superoxide anion produced by N ADPH oxidase on the membrane of neutrophils. Lucigenin-enhanced chemil uminescence (CL) to phorbol myristate acetate as respiratory burst and sorbitol levels in neutrophils after incubation with glucose and an a ldose reductase (AR) inhibitor, SNK-860 (SNK) were measured. Sorbitol levels increased from 0.210 +/- 0.029 nmol 10(7) cells(-1) in 5 mmol l (-1) glucose to 0.446 +/- 0.036 nmol 10(7) cells(-1) in 40 mmol l(-1) glucose, while CL decreased from 0.542 +/- 0.034 cpm cell(-1) in 5 mmo l l(-1) glucose to 0.430 +/- 0.018 cpm cell(-1) in 40 mmol l(-1) gluco se. The addition of 10 mu mol l(-1) SNK normalized the increased sorbi tol levels in neutrophils exposed to 40 mmol l(-1) glucose and improve d, but did not normalize, the decrease in CL induced by 40 mmol l(-1) glucose (p < 0.001). Galactose (40 mmol l(-1)) also reduced CL, which was improved by the addition of SNK (p < 0.01). These results suggest that impaired respiratory burst induced by high-glucose concentrations is caused by competition for NADPH resulting from increased polyol pa thway activity and/or glycation and that an AR inhibitor may be capabl e in part of preventing increased susceptibility to infection in diabe tic patients.