Cortisol enhancement of PTH-stimulated cyclic AMP accumulation in cultured fetal rat long bone rudiments

Abstract

Cortisol in concentrations from 10 nM to 10 µM produced a dose-related inhibition of basal and PTH¹-stimulated⁴⁵Ca and [³H]-hydroxyproline release from cultured fetal rat forelimb rudiments. PTH-stimulated cyclic AMP generation however was not diminished by cortisol; in contrast, at a concentration of 1 µM cortisol produced a 57% increase in PTH-stimulated bone cyclic AMP content. The stimulatory effect of cortisol on cyclic AMP content appeared to be the result of reduced phosphodiesterase activity, since this effect was not seen in the presence of 10 mM theophylline. It is concluded that cortisol inhibition of PTH-induced resorption in long bones is not accompanied by reduced cyclic AMP generation.