ERYTHROCYTE DEFORMABILITY IN ZINC-DEFICIENCY MEASURED AS A FUNCTION OF SHEAR-STRESS IN THE EKTACYTOMETER

Erythrocyte deformability was investigated as a potential biochemical Indicator of zinc status. Weanling, male Sprague-Dawley rats were fed ad libitum modified AIN-93G diets containing 3 mg zinc/kg diet (-Zn; n = 10) for 6 weeks. Control rats were pair-fed (+ZnPF; n = 10) or fed ad libitum (+ZnAL; n = 9) diets containing 50 mg zinc/kg diet. Zinc de ficiency significantly decreased plasma and tibia zinc concentration ( P < 0.001). Erythrocyte deformability was measured on whole blood as a function of shear stress in the ektacytometer. Elongation index, the ratio of length to width of the diffraction pattern of deforming cells , was plotted against shear stress. Maximum elongation index and the i nitial slope were determined from a function used to pr the sigmoid cu rve. As analyzed by one-factor analysis of variance, maximum elongatio n index, a measure of average deformability of the cell population, wa s significantly depressed in the -Zn and +ZnPF groups as compared with the +ZnAL group (P < 0.05). The mean (+/-SEM) maximum elongation inde x for each of the three groups was -Zn, 0.55 +/- 0.01; +ZnPF, 0.56 +/- 0.01: +ZnAL, 0.59 +/- 0.01. :The initial slope of the curve, a measur e of membrane deformability, was not altered by zinc deficiency. No ef fect of zinc deficiency was found for deformability of erythrocyte sus pensions heated at 48 degrees C for 6 min. Results of this study sugge st that erythrocyte deformability would not be a useful functional ind icator of zinc status. (C) Elsevier Science Inc. 1998.