Two mechanisms of inhibition by prostaglandin E2 of hormone-dependent cell cAMP in the rat collecting tubule.
The effect of exogenous prostaglandin E2 (PGE2) on hormone-dependent adenosine 3',5'-cyclic monophosphate (cAMP) accumulation was investigated by microradioimmunoassay in collecting tubules microdissected from the cortex (CCT) or outer medulla (MCT) of the rat kidney. Two phosphodiesterase inhibitors were used: either a xanthine derivative (isobutyl-methylxanthine (IBMX, 1 mM] active on all forms of phosphodiesterase or Ro 20-1724 (50 microM) active on the phosphodiesterase type III. A prostaglandin synthesis inhibitor was added to all media. In the presence of IBMX, 0.3 microM PGE2 inhibited by 39.1% the response induced in the CCT by the beta-adrenergic agonist isoproterenol (1 microM). Under the same experimental conditions, arginine vasopressin (AVP)-stimulated cAMP accumulation in CCT or MCT was not affected by PGE2. In the presence of Ro 20-1724, 0.3 microM PGE2 did not modify the response to 1 nM AVP in CCT but inhibited this response in MCT samples (mean inhibition: 52.7%). The inhibition by PGE2 was dose dependent with a maximum at 0.3 microM, observed for all concentrations of AVP tested (from 50 pM to 1 nM) and did not affect the concentration of AVP inducing half-maximal cAMP accumulation. In a second experimental series performed in the presence of adenosine deaminase, an A1-adenosine agonist [theta)-N6-(R-phenylisopropyl)adenosine (PIA, 0.1 microM] also decreased the response to 1 nM AVP in the MCT. The addition of an A1-adenosine antagonist relieved the effect of PIA but did not modify the inhibition observed with PGE2. Thus PGE2 decreased the synthesis of cAMP in beta-adrenergic sensitive cells in rat CCT and might affect the catabolism of AVP-dependent cAMP level rather than its synthesis in rat MCT.
Chabardès
D
D
Laboratoire de Physiologie Cellulaire, URA 219 CNRS, Collège de France, Paris.
Montégut
M
M
Zhou
Y
Y
Siaume-Perez
S
S
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D000241:Adenosine / Q000502:physiology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D015232:Dinoprostone / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007685:Kidney Tubules, Collecting / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction / Q000187:drug effects; D014970:Xanthines / Q000494:pharmacology
D014970:Xanthines; D001127:Arginine Vasopressin; D005576:Colforsin; D010660:Phenylisopropyladenosine; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; C046379:1,3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine; D000241:Adenosine; D015232:Dinoprostone; D007545:Isoproterenol; D015056:1-Methyl-3-isobutylxanthine; D007213:Indomethacin