Preliminary studies of somatomedin in vitro and in vivo in rats.

Abstract

This chapter discusses the studies of somatomedin in vitro and in vivo in rats. In a method described in the chapter, female hypophysectomized rats weighing 70–80 gm were purchased from the Hormone Assay Laboratories, Madison, Wisconsin, and were used for experiments 2–4 weeks after hypophysectomy. All animals were exposed to 14 hours of light per day and were fed Rockland Rat Chow ad libitum . Somatomedin activity was determined by measuring 35 SO 4 uptake in embryonic chick cartilage by the method of Hall. Pooled human plasma obtained from 800 voluntary donors was used as the standard, and the somatomedin activity of 1 ml of this plasma was defined as 1 unit (U). Somatomedin was extracted from human plasma and then purified. A fraction from pooled plasma containing lipoproteins, ceruloplasmin, transferrin, and some other α- and β-globulins was subjected to acid–ethanol extraction. Batches of 25 kg of this fraction corresponding to 1000 kg of plasma were subjected to extraction. Hypophysectomized female rats (Sprague–Dawley) weighing 60–75 gm at the time of ectomy were used in the in vivo study.