In vitro effects of fatty acids on the actions of serum on rat and pig cartilage.

It has been reported that fatty acids preferentially inhibit serum-stimulated incorporation of sulfate by embryonic chick cartilage, suggesting that they may interfere with the effects of a proposed mediator (serum somatomedin) of the actions of growth hormone (GH). This was studied further in mammalian cartilage. Butyrate and octanoate at concentrations of 0.5 to 5 mM produced a concentration-dependent inhibition of both basal and serum-stimulated sulfate and thymidine incorporation by costal cartilage from hypophysectomized rats. Butyrate also inhibited basal and serum-stimulated sulfate incorporation in cartilage from normal pigs and normal sucklings rats. In all 3 test systems, oleate (0.2--5 mM) bound to serum albumin (4 g/dl) was ineffective. There was no evidence that fatty acids preferentially inhibited the stimulation of sulfate incorporation produced by serum.