Acute Changes in Human Erythrocyte Insulin Receptors

Abstract

One hundred gram oral glucose tolerance tests (OGTT) were given to 6 normal human subjects after an overnight fast. From each subject, 100 ml of blood was collected at 0, 2 and 5 hours after the glucose load. Mononuclear cells (Boyum 1968) and erythrocytes (Gambhir, Archer and Bradley 1978) were prepared by the Ficoll-Hypaque technique and insulin binding was measured (Wachslicht-Rodbard et al. 1979;Gambhir et al. 1978). Monocytes were identified by latex bead ingestion and non-specific esterase staining in mixed mononuclear leukocytes and the binding to monocytes was calculated based on the percent of monocytes in mononuclear leukocytes.

Insulin Receptor Regulation in Human Mature Red Cells in vitro

“…Some reports suggested that, in vivo, RBC could acutely modify the affinity of their insulin receptors [6][7][8], We also tested this hypothesis in vitro. As shown in figure 3, a 3-hour preincubation does not produce any significant change in insulin receptor affinity.…”

“…Also Gambhir et al [5] suggested that RBC can internalize the 125I-insulin bound to insulin receptor. Moreover in vivo, acute changes in affinity of insulin receptors after OGTT [6,7] and muscular exercise [8] have been found in RBC. In this study we characterized the short-term regulation of insulin receptor on RBC, studying, in vitro, the ability of these cells to internalize the receptor-bound hor mone, to down regulate IR and to modify the IR affinity after insulin preincubation.…”