GLYCATED CALMODULIN FROM PLATELETS AS AN INDEX OF GLYCEMIC CONTROL

In an effort to test whether a significant fraction of calmodulin woul d become glycated within the life span of the platelet (10-14 days), w e monitored the kinetics of calmodulin glycation in vitro. Under the c onditions we used, the fraction of glycated calmodulin reached a maxim um (approximately 21%) within 10 days. We then extended the studies to human subjects. The intraplatelet concentrations of calmodulin and gl ycated calmodulin from age-matched type I diabetic subjects were monit ored by a combination of m-aminophenylboronate affinity chromatography and enzyme-linked immunosorbent assay. The results indicate that the concentrations of total intraplatelet calmodulin (nonglycated plus gly cated) were not dependent on the glycemic state of the subjects. Data from control and diabetic subjects showed a poor correlation between t he concentrations of glycohemoglobin and of glycated calmodulin. Howev er, a better correlation was obtained when glycated calmodulin concent rations were compared with those of serum fructosamine. The fraction o f glycated calmodulin in the control population (7.71% +/-0.75%) was s ignificantly (P <0.05) different from that of the diabetic population (21.6% +/- 1.26%). Given that the clinical role of the fructosamine as say remains controversial, estimation of glycated calmodulin in platel ets might be useful as a short time-window index of glycemic control.