Regulation of histamine- and UTP-induced increases in Ins(1,4,5)P3, Ins (1,3,4,5)P4 and Ca2+ by cyclic AMP in DDT1 MF-2 cells.
1. Stimulation of P2U-purinoceptors with UTP or histamine H1-receptors with histamine gave rise to the formation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) in DDT1 MF-2 smooth muscle cells. 2. Stimulation of P2U-purinoceptors or histamine H1-receptors caused an increase in cytoplasmic Ca2+, consisting of an initial peak, representing the release of Ca2+ from internal stores and a sustained phase representing Ca2+ influx. 3. The P2U-purinoceptor-mediated Ca(2+)-entry mechanism was more sensitive to UTP than Ca(2+)-mobilization (EC50: 3.3 microM +/- 0.4 microM vs 55.1 microM +/- 9.2 microM), in contrast to these processes activated by histamine H1-receptors (EC50: 5.8 microM +/- 0.6 microM vs 3.1 microM +/- 0.5 microM). 4. Pre-stimulation of cells with several adenosine 3':5'-cyclic monophosphate (cyclic AMP) elevating agents, reduced the histamine H1-receptor-mediated formation of Ins(1,4,5)P3 and Ins(1,3,4,5)P4. Forskolin completely inhibited Ins(1,4,5)P3 formation (IC50: 158 +/- 24 nM) whereas Ins(1,3,4,5)P4 formation was inhibited by only 45% (IC50: 173 +/- 16 nM). The P2U-purinoceptor-mediated production of these inositol phosphates was not affected by cyclic AMP. 5. Forskolin and isoprenaline reduced the histamine-induced increase in cytoplasmic Ca2+, as measured in Ca2+ containing medium and in nominally Ca(2+)-free medium but did not change the UTP-induced increase in cytoplasmic Ca2+. 6. These results clearly demonstrate that cyclic AMP differentially regulates components of the histamine induced phospholipase C signal transduction pathway. Furthermore, cyclic AMP does not affect the phospholipase C pathway activated by stimulation of P2U-purinoceptors in DDT1 MF-2 cells.
Sipma
H
H
Department of Pharmacology/Clinical Pharmacology, Groningen Institute for Drugs Studies, University of Groningen, The Netherlands.
Duin
M
M
Hoiting
B
B
den Hertog
A
A
Nelemans
A
A
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008647:Mesocricetus; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D011969:Receptors, Histamine H1 / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000187:drug effects; D010738:Type C Phospholipases / Q000378:metabolism; D014544:Uridine Triphosphate / Q000494:pharmacology*; D014649:Vas Deferens / Q000187:drug effects / Q000378:metabolism
D007295:Inositol Phosphates; D011969:Receptors, Histamine H1; D018048:Receptors, Purinergic P2; C081655:inositol-1,3,4,5-tetrakisphosphate; D005576:Colforsin; D006632:Histamine; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D002118:Calcium; D014544:Uridine Triphosphate