INSULIN INTERNALIZATION STUDY IN CORD BLOOD ERYTHROCYTES. (E)

Insulin internalization has been extensively studied in target cells, this process has not been characterized in human (E). Cord blood (E) were incubated with 125I-insulin at 4°C.or at 37°C. in the presence and absence of Methylamine (M) which induces intracellular accumulation of insulin or Phenylarsine oxide (P) a well known inhibitor of endocytosis. At various time points, insulin binding (I.B.), haemolysis and degradation were determined, and insulin internalization was quantified using an acid extraction technique. Our results show that (M) and (P) failed to alter (I. B.) in (E).Insulin bound at 4°C. was 90-95% extractable and TCA precipitable while at 37°C. with increasing time of incubation the extractability of cell bound insulin and the proportion of intact, undegraded, extractable insulin decrease. In adition (I.B.) degradation and non-extractable acid insulin were increased by haemolysis even at 4°C.