ROLE OF ALBUMIN GLYCATION ON THE ERYTHROCYTE AGGREGATION - AN IN-VITRO STUDY

The increased erythrocyte aggregation observed in diabetes mellitus is mainly due to changes in the balance between aggregating factors and anti-aggregating ones, like albumin. Since chronic hyperglycaemia resu lts in protein glycation, we examined the effect of in vitro glycation of albumin on its anti-aggregating role with blood from 29 Type 1 dia betic patients and 29 healthy controls. After the addition of glycated and unglycated albumin, samples had a glycation level of 24 % for hea lthy controls and 28 % for diabetic patients. Erythrocyte aggregation was determined by the analysis of the light backscattered by a blood s uspension. Erythrocytes from healthy controls suspended in glycated al bumin had significantly higher rates of rouleaux formation (p < 0.01) than in unglycated albumin and increased cohesion of rouleaux (p < 0.0 5). The erythrocyte aggregation in diabetic patients underwent similar changes (p < 0.01). The time-resolved fluorescence of the single tryp tophan residue was monitored to describe the changes in the conformati onal equilibrium of albumin. The lifetime data showed that the increas es in the two lifetime components and in the relative proportion of th e major lifetime are in agreement with a conformational change in albu min after glycation. Thus, the changes in albumin conformation could b e responsible for the smaller hypoaggregating effect of glycated album in.