Effect of glucocorticoids, butanol extraction of serum and adrenalectomy on somatomedin levels in the rat.

Serum from adrenalectomized rats was equipotent with serum from non-adrenalectomized animals when measured in a rat cartilage somatomedin bioassay. Extraction with butanol of sera from normal or adrenalectomized rats reduced their potency in the somatomedin bioassay rather than increasing it as has been previously reported. Butanol-soluble inhibitors of cartilage metabolism were found in sera from both normal and adrenalectomized rats. Cortisol and corticosterone, up to mildly supraphysiological levels, were found to have no effect on basal cartilage metabolism. These results suggest that physiological levels of glucocorticoids do not exert an inhibitory effect on the uptake of 35SO4(2-) into immature rat cartilage. Since butanol-soluble inhibitors of cartilage metabolism were found in adrenalectomized rat serum it is unlikely that these substances are glucocorticoids.