Regulation of intracellular calcium by extracellular nucleotides in pig tracheal submucosal gland cells.
The mechanisms by which extracellular nucleotides (ATP and UTP) regulate intracellular Ca2+ in cultured pig tracheal gland cells were studied. The calcium response induced by ATP or UTP was composed of a peak response and a steady plateau. In the absence of extracellular Ca2+, the peak response of the cells to both ATP and UTP was smaller, and no subsequent plateau was observed. After treatment of the cells with pertussis toxin, the peak response to UTP was significantly smaller and no plateau was seen even in the presence of extracellular Ca2+, but pertussis toxin did not change the effect of ATP. Pretreatment with U107, a phospholipase C inhibitor, almost abolished the calcium response to both ATP and UTP. Immunocytochemistry showed that in these cells, the IP3 receptor was localized in the cytoplasm (including the endoplasmic reticulum) of the cells. Our results indicate that both release of calcium from the intracellular store and Ca2+ influx across the cell membrane contribute to the mobilization of [Ca2+]i upon stimulation with nucleotides, that ATP and UTP regulate intracellular Ca2+ predominantly via the G protein-phospholipase C-IP3 pathway, and that ATP and UTP may act via distinct subtypes of P2Y receptors.
Zhang
A L
AL
Department of Medical Cell Biology, University of Uppsala, Sweden. ailing.zhang@medcellbiol.uu.se
Roomans
G M
GM
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D009711:Nucleotides / Q000502:physiology*; D037342:Pertussis Toxin; D013552:Swine; D014132:Trachea / Q000187:drug effects / Q000502:physiology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D014544:Uridine Triphosphate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D009711:Nucleotides; D010566:Virulence Factors, Bordetella; D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D002118:Calcium; D014544:Uridine Triphosphate