DIFFERENTIAL RESIN BINDING OF INSULIN IN SERUM1

Abstract

A method of interaction analysis by the differential resin adsorption of insulin has been designed which quantitated the binding of insulin by sera in vitro. Sera containing insulin-I¹³¹ were equilibrated in tubes with measured volumes of anionic resin. Following equilibration the tubes were removed and the radioactivity was measured in a well-type scintillation detector. The resins were then washed with distilled water in order to remove the radioactivity that was not resin bound and the tubes were recounted. The radioactivity remaining on the resin divided by the initial radioactivity measured the fraction of hormone bound by the resin (“resin index”)- A low resin index reflected increased binding of hormone by serum, and vice versa. Increased binding of insulin-I¹³¹ by the sera from insulin responsive diabetics was demonstrated when compared with sera from normal subjects. The ability of the resin to bind insulin in serum depended to some extent upon factors other than the competitive binding of insulin by the serum proteins. There was no relationship between the degree of insulin binding by sera from insulin treated diabetics and insulin tolerance.