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Studies of insulin binding in children using human erythrocytes in small amounts of blood
Insights
Children
Area of Science:
- Endocrinology
- Cell Biology
- Metabolic Research
Background:
- Insulin's primary action is mediated through specific receptors on target cells.
- Erythrocytes (red blood cells) possess insulin receptors, offering a potential model for studying insulin binding.
- Understanding insulin receptor dynamics in pediatric populations is crucial for metabolic health assessment.
Purpose of the Study:
- To investigate and quantify specific insulin binding by erythrocytes in children.
- To compare insulin receptor characteristics in children's erythrocytes with those of adults and cord blood.
- To assess the feasibility of using erythrocyte insulin binding as a biomarker in pediatric metabolic disorders.
Main Methods:
- Performed complete insulin binding studies using small blood volumes (as little as 5 ml).
- Utilized competition-inhibition curves and nonlinear Scatchard plots to characterize receptor behavior.
- Compared insulin receptor numbers and binding affinities across different age groups (infants, children, adults).
Main Results:
- Erythrocytes from children exhibited significantly higher numbers of insulin receptors per cell compared to adults.
- Cord blood erythrocytes showed the greatest number of insulin receptors per cell, with similar affinity to adults and children.
- Total insulin bound by erythrocytes did not differ between children and adults within the physiologic range, but was higher in cord blood.
Conclusions:
- Erythrocytes demonstrate specific insulin binding with characteristics similar to established insulin target tissues.
- Pediatric erythrocytes, particularly from cord blood, possess a higher density of insulin receptors than adult erythrocytes.
- Erythrocyte insulin binding measurement is a reliable method, suitable for studying infants and children with carbohydrate metabolism disorders.
Abstract:
We have demonstrated specific insulin binding by the erythrocytes (RBCs) of children. Complete binding studies were done using as little as 5 ml of blood. The receptors exhibited competition-inhibition curves and nonlinear Scatchard plots similar to those reported for insulin target tissues, such as the hepatocyte and the adipocyte. Compared with those from adults, the RBCs from children had significantly greater numbers of insulin receptors per cell (P less than 0.05). The total insulin bound by the RBCs from both children and adults, however, was not different over the physiologic range of insulin concentrations. Cord blood RBCs showed greater numbers of receptors per cell than did those from either children or adults; however, the affinity for insulin was similar in both groups. The total amount of insulin bound by cord blood was significantly greater than that in either children (P less than 0.01) or adults (P less than 0.05) over the physiologic range of insulin concentrations. The method used to measure insulin binding by erythrocytes and relatively little intra- and interassay variability, and there was little diurnal variation in binding. Storage of heparinized blood at 4 degree C for 24--36 h had no effect on insulin binding by the RBCs. We conclude that the measurement of insulin binding by RBCs from small volumes of blood may be particularly useful in the study of infants and children with disorders of carbohydrate metabolism to elucidate the role, if any, of abnormal receptor function in their condition.