Ontogeny of purinergic receptor-regulated Ca2+ signaling in mouse cortical collecting duct epithelium.
Changes in ATP-induced increase in [Ca2+](i) during collecting duct ontogeny were studied in primary monolayer cultures of mouse ureteric bud (UB) and cortical collecting duct (CCD) cells by Fura-PE3 fluorescence ratio imaging. In UB (embryonic day E14 and postnatal day P1) the ATP-stimulated increase (EC(50) approximately 1 microM) in fluorescence ratio (DeltaR(ATP)) was independent of extracellular Ca2+ and insensitive to the P2 purinoceptor-antagonist suramin (1 mM). From day P7 onward when CCD morphogenesis had been completed DeltaR(ATP) increased and became dependent on extracellular Ca2+. This ATP-stimulated Ca2+ entry into CCD cells was non-capacitative and suramin (1 mM)-insensitive, but sensitive to nifedipine (30 microM) and enhanced by Bay K8644 (15 microM), a blocker and an agonist of L-type Ca2+ channels, respectively. Quantitative RT-PCR demonstrated similar mRNA expression of L-type Ca2+ channel alpha1-subunit, P2Y(1), P2Y(2), and P2X(4b) purinoceptors in UB and CCD monolayers while the abundance of P2X(4) mRNA increased with CCD morphogenesis. In conclusion, both embryonic and postnatal cells express probably P2Y(2)-stimulated Ca2+ release from intracellular stores. With development, the CCD epithelium acquires ATP-stimulated Ca2+ entry via L-type Ca2+ channels. This pathway might by mediated by the increasing expression of P2X(4)-receptors resulting in an increasing ATP-dependent membrane depolarization and activation of L-type Ca2+ channels.
Tschöp
Johannes
J
Physiologisches Institut, Ludwig-Maximilians-Universität, Munich, Germany.
Braun
Gerald S
GS
Borscheid
René
R
Horster
Michael F
MF
Huber
Stephan M
SM
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D004848:Epithelium / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011983:Receptors, Purinergic / Q000235:genetics / Q000378:metabolism*; D014513:Ureter / Q000166:cytology / Q000187:drug effects / Q000196:embryology / Q000378:metabolism
D020746:Calcium Channels, L-Type; D012333:RNA, Messenger; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D002118:Calcium