The effect of high glucose on polyol pathway activity and myoinositol metabolism in cultured human endothelial cells.

Cultured human endothelial cells were incubated with high glucose (27.5 mmol/l) supplemented medium for 0, 2, 6, 12, 24 and 48 h. Lactate dehydrogenase was assayed as a measure of cell number. Sorbitol and myoinositol were determined as trimethyl silyl derivatives using gas chromatography mass spectrometry. Sorbitol, after an initial lag phase of 2 h, accumulated rapidly to plateau at 2 to 3 fold control value by 24 h, no further increase being seen over a further 24 h (Baseline, 1.31 +/- 0.36, 24 h 3.50 +/- 0.74 pmol sorbitol/unit lactate dehydrogenase; p less than 0.001). There was no change in myoinositol levels over the 24 h period. Sorbitol accumulation occurred at glucose concentration greater than 18.1 mmol/l and only returned to baseline levels after 24 h of incubation in normal medium (glucose levels 5.9 mmol/l). Sorbitol levels are increased by incubation of endothelial cells at high glucose levels but myoinositol levels remain unchanged.