Regulation of transcervical permeability by two distinct P2 purinergic receptor mechanisms.
Micromolar concentrations of ATP stimulate biphasic change in transepithelial conductance across CaSki cultures, an acute increase (phase I response) followed by a slower decrease (phase II response). Phase I and phase II responses involve two distinct calcium-dependent pathways, calcium mobilization and calcium influx. To test the hypothesis that phase I and phase II responses are mediated by distinct P2 purinergic receptors, changes in permeability were uncoupled by blocking calcium mobilization with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) or by lowering extracellular calcium, respectively. Under these conditions ATP EC(50) was 25 microM for phase I response and 2 microM for phase II response. The respective agonist profiles were ATP > UTP > adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma S) = N(6)-([6-aminohexyl]carbamoylmethyl)adenosine 5'-triphosphate (A8889) > GTP and UTP > ATP > GTP = A8889 > ATP-gamma S. Suramin blocked phase I response and ATP-induced calcium mobilization, whereas pyridoxal phosphate-6-azophenyl-2',4-disulfonic acid (PPADS) blocked phase II response and ATP-augmented calcium influx. ATP time course and pharmacological profiles for phase II response and augmented calcium influx were similar, with a time constant of 2 min and a saturable concentration-dependent effect (EC(50) of 2-3 microM). RT-PCR experiments revealed expression of mRNA for both the P2Y(2) and P2X(4) receptors. These results suggest that the ATP-induced phase I and phase II responses are mediated by distinct P2 purinergic receptor mechanisms.
Gorodeski
George I
GI
Department of Obstetrics and Gynecology, University MacDonald Women's Hospital, University Hospitals of Cleveland, Ohio 44106, USA. gig@po.cwru.edu
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002584:Cervix Uteri / Q000166:cytology*; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058848:Receptors, Purinergic P2X4; D058473:Receptors, Purinergic P2Y2; D013498:Suramin / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology
D000970:Antineoplastic Agents; D002614:Chelating Agents; C548226:P2RX4 protein, human; C546385:P2RY2 protein, human; D010975:Platelet Aggregation Inhibitors; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058848:Receptors, Purinergic P2X4; D058473:Receptors, Purinergic P2Y2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; C022571:adenosine 5'-O-(3-thiotriphosphate); D004533:Egtazic Acid; D011732:Pyridoxal Phosphate; D013498:Suramin; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium; D014544:Uridine Triphosphate