Decrease in Serum Receptor-Reactive Somatomedin in Diabetes

Abstract

Somatomedin in rat serum has been measured by a sensitive radioreceptor assay using ¹²⁵I-labelled human somatomedin and human placental membrane. In rats made diabetic with strepotzotocin, receptor-reactive somatomedin levels were decreased by up to 75%. The decrease followed the time course of increasing serum glucose and occurred to the same extent in rats aged between 4 and 40 weeks. Endogenous serum receptor-reactive somatomedin appeared exclusively in high molecular weight fractions on gel chromatography. In diabetes the decreased somatomedin was due to a fall in this high molecular weight activity, but was not accompanied by a fall in somatomedin binding protein. These results suggest a role for insulin in maintaining serum somatomedin levels.

Key words

Somatomedin - Radioreceptor Assay - Diabetes - Binding Protein