The effect of PPADS as an antagonist of inositol (1,4,5)trisphosphate induced intracellular calcium mobilization.
1. Brain capillary endothelial cells responded to uridine 5'-triphosphate (UTP) and adenosine 5'-triphosphate (ATP) by activation of phospholipase C and by large changes in [Ca2+]i. These cells expressed mRNA sequences identical to the sequence of the P2Y2-purinoceptor of rat pituitaries. 2. Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) at 100 microM did not prevent UTP and ATP induced accumulations of total [3H]-inositol (poly)phosphates. It inhibited UTP and ATP induced intracellular Ca2+ mobilization (IC50 = 30 microM) by non competitive mechanism. 3. PPADS (100 microM) inhibited endothelin-1 induced accumulation of total [3H]-inositol (poly)phosphates by less than 20% and prevented most of endothelin-1 induced intracellular Ca2+ mobilization (IC50 = 30 microM). 4. PPADS (100 microM) had no action on ionomycin induced intracellular Ca2+ mobilization. 5. Microinjection of inositol (1,4,5)trisphosphate (InsP3) into Xenopus oocytes induced large Ca2+ activated Cl- currents that were prevented by heparin and by PPADS. 6. It is concluded that PPADS does not recognize rat P2Y2-purinoceptors and prevents UTP and ATP induced intracellular Ca2+ mobilization by a non-specific mechanism that could involve the inhibition of InsP3 channels.
Vigne
P
P
Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Université de Nice Sophia Antipolis, Valbonne, France.
Pacaud
P
P
Urbach
V
V
Feolde
E
E
Breittmayer
J P
JP
Frelin
C
C
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000098:blood supply; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry; D003600:Cytosol / Q000378:metabolism; D004347:Drug Interactions; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000096:biosynthesis; D007424:Intracellular Fluid / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology; D014544:Uridine Triphosphate / Q000037:antagonists & inhibitors / Q000494:pharmacology
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D010975:Platelet Aggregation Inhibitors; D018160:Receptors, Cytoplasmic and Nuclear; D018048:Receptors, Purinergic P2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D014544:Uridine Triphosphate