Establishment and preliminary clinical application of radioreceptor assay for the determination of insulin in human sera
Zhu, J.H.; Feng, Y.M.; Wang, H.Y.; Xu, J.M.
Chinese Medical Journal 97(11): 865-870
1984
ISSN/ISBN: 0366-6999 PMID: 6443281 Document Number: 232235
A simple radioreceptor assay (RRA) of insulin was established by using insulin receptor on human placental membrane (HPM). In this system, 60-70% of bound 125I-insulin can be displaced when native insulin (338 mU/ml) is added. This method is suitable for clinical application as shown by its sensitivity, accuracy and precision. Serum insulin concentration of normal adults, patients with diabetes mellitus and other diseases determined both by RRA and radioimmunoassay (RIA) tend to be coincident. Experiments showed that RRA as well as RIA, may distinguish nondiabetic and diabetic subjects, and patients with insulin dependent diabetes mellitus (IDDM) and noninsulin dependent diabetes mellitus (NIDDM). Fasting sera obtained from 40 normal adults were determined by RRA and RIA simultaneously. The concentrations of insulin were 11.25 .+-. 4.2 .mu.U/ml and 11.19 .+-. 3.9 .mu.U/ml, respectively. The insulin release curves of 9 IDDM patients measured by RRA and RIA were consistent. However, the values of insulin release of 7 normal adults and 8 NIDDM patients determined by RRA were slightly lower than those determined by RIA. Before and after oral administration of nifedipine in 4 cases of coronary heart diseases, insulin release curves, determined by RIA did not change significantly, but from those obtained by RRA, the release curves of insulin were observed to be much lower or the peak value was delayed. Results are consistent with those of oral glucose tolerance test (OGTT) and suggest that RRA may be more specific than RIA.