P2 receptor regulation of [Ca2+]i in cultured mouse mesangial cells.
Experiments were performed to establish the pharmacological profile of purinoceptors and to identify the signal transduction pathways responsible for increases in intracellular calcium concentration ([Ca(2+)](i)) for cultured mouse mesangial cells. Mouse mesangial cells were loaded with fura 2 and examined using fluorescent spectrophotometry. Basal [Ca(2+)](i) averaged 102 +/- 2 nM (n = 346). One hundred micromolar concentrations of ATP, ADP, 2',3'-(benzoyl-4-benzoyl)-ATP (BzATP), ATP-gamma-S, and UTP in normal Ca(2+) medium evoked peak increases in [Ca(2+)](i) of 866 +/- 111, 236 +/- 18, 316 +/- 26, 427 +/- 37, and 808 +/- 73 nM, respectively. UDP or 2-methylthio-ATP (2MeSATP) failed to elicit significant increases in [Ca(2+)](i), whereas identical concentrations of adenosine, AMP, and alpha,beta-methylene ATP (alpha,beta-MeATP) had no detectable effect on [Ca(2+)](i). Removal of Ca(2+) from the extracellular medium had no significant effect on the peak increase in [Ca(2+)](i) induced by ATP, ADP, BzATP, ATP-gamma-S, or UTP compared with normal Ca(2+); however, Ca(2+)-free conditions did accelerate the rate of decline in [Ca(2+)](i) in cells treated with ATP and UTP. [Ca(2+)](i) was unaffected by membrane depolarization with 143 mM KCl. Western blot analysis for P2 receptors revealed expression of P2X(2), P2X(4), P2X(7), P2Y(2), and P2Y(4) receptors. No evidence of P2X(1) and P2X(3) receptor expression was detected, whereas RT-PCR analysis reveals mRNA expression for P2X(1), P2X(2), P2X(3), P2X(4), P2X(7), P2Y(2), and P2Y(4) receptors. These data indicate that receptor-specific P2 receptor activation increases [Ca(2+)](i) by stimulating calcium influx from the extracellular medium and through mobilization of Ca(2+) from intracellular stores in cultured mouse mesangial cells.
Rivera
Ian
I
Department of Physiology, Medical College of Georgia, Augusta, Georgia 30912-3000, USA.
Zhang
Shali
S
Fuller
B Scott
BS
Edwards
Brentan
B
Seki
Tsugio
T
Wang
Mong-Heng
MH
Marrero
Mario B
MB
Inscho
Edward W
EW
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002460:Cell Line; D003470:Culture Media / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D050527:Mesangial Cells / Q000378:metabolism*; D051379:Mice; D009994:Osmolar Concentration; D058913:Purinergic Agonists; D011743:Pyrimidines / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000819:agonists; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical
D003470:Culture Media; D058913:Purinergic Agonists; D011743:Pyrimidines; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018048:Receptors, Purinergic P2; D002118:Calcium