Effects of Puromycin and Actinomycinin Vitroon Sulfate Incorporation by Cartilage of the Rat and Its Stimulation by Serum Sulfation Factor and Insulin

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Abstract
The effects of puromycin and actinomycin on sulfate incorporation in vitro by cartilage from normal and hypophysectomized rats were determined. Tissue was incubated in a medium containing 14 amino acids and glucose. Sulfate incorporation was measured with (S35) sulfate. Both antibiotics profoundly inhibited sulfate incorporation by cartilage from normal and hypophysectomized animals. Maximal inhibition with actinomycin was less than with puromycin in cartilage from normal rats but was nearly equal to puromycin in cartilage from hypophysectomized rats. Maximal inhibitory concentrations of either antibiotic abolished the sulfation-promoting actions of serum sulfation factor and insulin. In cartilage from normal rats, actinomycin inhibited (Cl4)uridine incorporation into RNA, and either antibiotic inhibited (C14)leucine incorporation into a TCA [trichloro-acetic acid]-insoluble fraction of protein. In addition, either agent decreased the very low basal O uptake and slightly decreased the release of lactic acid by this tissue. In cartilage from hypophysectomized rats, (C14) leucine incorporation into TCA-insoluble protein was inhibited also by either antibiotic. The data support previous indications that sulfation in cartilage of the rat and its stimulation by either serum sulfation factor or insulin are dependent upon protein synthesis.