D-Glucose additive protects against osmotic-induced decrease in erythrocyte filterability

Glucose has long-term effects on erythrocyte filterability owing to sorbito l accumulation and glycosylation of intracellular proteins, but glucose eff ects prior to these long-term metabolic consequences have not been studied to the same extent. D-glucose is osmotically inert in erythrocytes because of facilitated diffusion. Erythrocyte volume regulation, hemolysis and filt erability were studied with reference to effects of glucose derivatives dis solved in water. Control situations were water alone or buffer. Salt-stock dilution by water, D-glucose, or 3-O-M-glucose in water (both 570 mmol/L ad ditives) created volume increases of 4.0 +/- 0.2%, 3.4 +/- 0.5% and 3.3 +/- 0.2%, respectively, whereas L-glucose resulted in a 2.2 +/- 0.4% volume de crease (all p < 0.001 versus baseline, mean values +/- SEM). D-glucose at a final concentration 30 mmol/L did not display any osmotic properties. Desp ite erythrocyte swelling, electrolyte-free glucose did not induce any signi ficant changes in filterability with either 3-<mu>m or 5-mum filters. 3-O-M -glucose gave a 7.8 +/- 1.4% decrease in 3-mum filterability (mean value +/ - SEM, p < 0.001), but not to the same extent as by water alone at the corr esponding dilution rate (31.7 +/- 3.5%, mean value +/- SEM, p < 0.001). L-g lucose caused a 2.0 +/- 0.8% decrease in filterability across the 5-mum (me an value +/- SEM, p < 0.05), but not with the 3-<mu>m filters. Stressing th e glucose transport system further, to simulate the water-like properties o f electrolyte-free glucose during intravenous infusion, we found that gluco se becomes osmotically active and prevents hemolysis at these extreme conce ntrations (>114 mmol/L). We conclude that an in vivo concentration range of D-glucose protects the erythrocytes from a decreased filterability induced by osmotic swelling but without having any osmotic properties.