Effects of Prostaglandins on Adenosine 3′,5′- Monophosphate Content and Adenylate Cyclase Activity in Dispersed Bovine Parathyroid Cells*

Selected prostaglandins (PGs) stimulated adenylate cyclase activity in parathyroid cells at concentrations as low as 10-6 M, and effects became maximal at 10-5-10-4 M. The order of potency was PGE1 ≥ PGE2 > PGF2α, paralleling doseresponse characteristics of these agents in stimulating the accumulation of cAMP in intact cells. Maximal stimulation was found with the addition of 10-4 M GTP. PGF2α has previously been shown to suppress cAMP accumulation in the intact parathyroid cell. This agent did not affect the (-)isoproterenol stimulation of adenylate cyclase in either the lysed cell particulate preparation or the complete homogenate regardless of GTP concentration or the addition of EGTA (1 mM). PGF2α did not impair (-)isoproterenol binding to the β-adrenergie receptor. Neither PGE2 nor PGF2α at concentrations as high as 10-4 M, affected phosphodiesterase (PDE) activity, nor did high concentrations (10-3 M) of the PDE inhibitor methylisobutylxanthine prevent the PGF2α, suppression of cellular cAMP levels....