Abstract

For the purpose of clinical application of insulin receptor assay, we studied the specific binding of '"l-insulin in vitro to circulating erythrocytes from 10 normal volunteers, 15 patients with non- obese diabetes mellitus and 15 patients with chronic renal failure. The speeific ""l-insulin binding was measured by competitive binding of ""I-iinsulin and unlabeled insulin to insulin receptor of erythrocytes, The results were as fallaws: 1) The mean maximal percent specific ""I-insulin bindings of the normai sbjects, the patients with diabetes mellitus and the patients with chronic renal failure were 6.6+-1.9 4. 3+-- 0.6 and 3.4+-0.5% ,respectively. 2) The maximal insulin receptor concentration calculated by Scatchard analysis were 0.9+- 0.2 and 0.4+-0.1 ng/4.4 x 1 Gcells in the patients with diabetes meIIitus and the patients with chronic renal faiiure, respeetively, both being significantly lower than 2.7+-0.8 ng/4.4 x 10' cells in the normal suhjects(p<0.05), 3) The mean number of recepter sites per cells obtained by multiplying by Avogadro's number were 10.1+-1.5 in the patients with chronic renal failure and 22.4+-4.3 in the patients with diabetes mellitus, hoth being significantly lower than 67.2 +-18.3 in the narmal subjects(p<0.05). 4) The mean erythrocyte rceptor affinity for insulin was 3.0+- 0.4 M' x 10' in the patients with chronic renal failure, being significantly higher than 1,9+- 0.5 and 2. 0+-0. 2 M ' x 10" in tha normal subjects and patients wlth diabetes mellitus(p< 0.05). 5) The mean plasma insulin level was 39.9+- 15.3, 43.3+-21.4 and 40.8+-19.5 pU/ml in the normal subjects, the patients with diabetes mellitus and the patients with chronic renal failure, respectively. It is concluded that the low leveI of insulin receptor concentration of the cell may be contributory factor to glucose intolerance or insulin resistance in the patients with diabetes mellitus and in the patients with chronic renal failure.