HIGH D-GLUCOSE INDUCES ALTERATIONS OF ENDOTHELIAL-CELL STRUCTURE IN ACELL-CULTURE MODEL

Diabetes mellitus leads to micro-and macroangiopathy with endothelial dysfunction. To investigate the direct influence of high glucose on en dothelial cell structure and possible pharmacologic effects, seven dif ferent experimental protocols were carried out on endothelial cells in culture. There were four control groups with either 5 mM D-glucose al one, 5 mM D-glucose plus 15 mM L-glucose (for osmotic control), 5 mM D -glucose plus 500 nhl celiprolol, or 5 mM D-glucose plus 57 nM nitrend ipine. Three experimental groups had either 20 mM D-glucose alone, 20 mM D-glucose plus 500 nM celiprolol or 20 mM D-glucose plus 57 nM nitr endipine. Treatment of all groups started at the third passage of the cells and lasted until confluence was reached (5-8 days). The endothel ial cells were fixed in paraformaldehyde and stained either with hemat oxylin-eosin solution, with nitro blue tetrazolium for nicotinamide ad enine dinucleotide phosphate (NADPH)-diaphorase staining, or actin sta ining with phalloidin was carried out. For quantitative analysis of th e histologic specimens, the slides were viewed via a microscope and a videocamera. The pictures were converted digitally and could be analyz ed with the videopicture-analyzing system, JAVA. In the four control g roups, neither treatment with 15 mM L-glucose nor administration of ce liprolol or nitrendipine had an effect on cell, cytoplasm, and nuclear area. The number of giant or polynuclear cells and the histochemical NADPH-diaphorase activity were not altered. Incubation of endothelial cells with 20 mM D-glucose for 5-8 days resulted in a significant incr ease in total and cytoplasmic area, as well as in the number of giant and polynuclear cells, whereas the nuclear area and the NADPH-diaphora se activity were significantly reduced. Concomitant treatment with cel iprolol was able to reverse these alterations in endothelial structure significantly but had only a weak effect on the NADPH-diaphorase. Nit rendipine had no beneficial effect on the high D-glucose-induced cell alterations. The actin staining of the control cells showed the typica l actin pattern with most of the actin filaments arranged at the perip hery of the cells. Administration of 20 mM D-glucose resulted in a dis turbance of the actin pattern, with most of the actin filaments now ar ranged in the middle of the cells. However. neither celiprolol nor nit rendipine exhibited a significant influence on this altered actin stru cture. High D-glucose treatment over several daps thus leads to severe changes in endothelial cell structure, and celiprolol may have a bene ficial effect on these hyperglycemia-induced cell alterations.