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KMID : 0378019830260100075
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New Medical Journal
1983 Volume.26 No. 10 p.75 ~ p.90
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Studies of Erythrocyte Insulin Receptor in Patients with Diabetes Mellitus and Other Diseases Associated with Abnormal Glucose Metabolism
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金光源/Kim, Kwang Won
金榮卨/金鮮宇/崔永吉/Kim, Young Seol/Kim, Sun Woo/Choi, Young Kil
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Abstract
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To evaluate the alterations of insulin receptors in patients with type. II diabetes mellitus (noninsulin-dependent diabetes mellitus, NIDDM) and abnormal glucose metabolism, the author performed erythrocyte insulin receptor assay in 8 cases of normal control, 8 cases of NIDDM, 1 case of type I diabetes mellitus (insulin-dependent diabetes mellitus, IDDM), 1 case of diabetes mellitus secondary to chronic pancreatitis, 1 case of insulinoma, and 1 case of iatrogenic Cushing´s syndrome, who were admitted to Kyung-Hee Medical Center.
For insulin binding to erythrocyte, the author used the method introduced by Gambhir et al. Blood, 10ml, was drawn into a heparinized tube and centrifuged, the plasma was aspirated. The cells were diluted 1 : 1 with normal saline and separated through Ficoll-Hypapue gradients. The erythrocytes were resuspended to a final concentration 4. 5 x 10´ erythrocyte per milliliter in buffer G (pH 8. 0) incubated with labeled insulin (porcine, Cambridge Nuclear. 90pci/kg) and unlabeled insulin over a range of concentrations from 0 to 10b ng per milliliter for 3. 5 hours at 15°C. After incubation, 0.2m1 replicate aliquots were transferred to chilled microfuge tubes that contained 200ul of dibutylphthalate. After centrifugation, the supernatant was aspirated and discarded. Radioactivity in the red cell pellet was counted in a gamma counter (Beckman, Model Gamma 9000). The methods of analysis were percent of labeled insulin bound to erythrocyte, Scatchard analysis, average number of insulin binding sites per erythrocyte, and affinity constant of the empty sites (Ke). The results were as follows: (1) percent of labeled insulin bound in NIDDM (6.9±1. 1%) was significantly lower than that of normal control group (10. 1±2.7%) (p<0.01), (2) receptor numbers per red cells in NIDDM (868±308) was significently fewer than that of normal control group (1425±181) (p<0. 005), (3) empty site affinity (Kex10´ M-1) in NIDDM (1.26±0. 46) was not significantly different from that of normal control group (1. 12±0. 37), (4) basal insulin levels and receptor numbers in NIDDM did not correlate (r=-0.28), and (5) similar studies in other patients with abnormal glucose metabolism showed variable results.
Above results indicated that (1) erythrocyte was useful model as insulin receptor assay, (2) defect at the level of insulin receptor, especially decrease in number of receptor, was responsible for insulin resistance, and (3) other defect such as post-receptor defect, might also be an additional mechanism of insulin resistance.
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KEYWORD
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