Extracellular nucleotides regulate cellular functions of podocytes in culture.
Extracellular nucleotides are assumed to be important regulators of glomerular functions. This study characterizes purinergic receptors in podocytes. The effects of purinergic agonists on electrophysiological properties and the intracellular free Ca(2+) concentration of differentiated podocytes were examined with the patch-clamp and fura 2 fluorescence techniques. mRNA expression of purinergic receptors was investigated by RT-PCR. Purinergic agonists depolarized podocytes. Purinergic agonists similarly increased intracellular free Ca(2+) concentration of podocytes. The rank order of potency of various nucleotides on membrane voltage and free cytosolic calcium concentration was UTP approximately UDP > [adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S)] > ATP > 2-methylthioadenosine 5'-triphosphate (2-MeS-ATP) > 2'- and 3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP) > ADP-beta-S. alpha,beta-Me-ATP was without effect. In the presence of UTP, BzATP did not cause an additional depolarization of podocytes. Incubation of cells with ATP or BzATP did not induce lactate dehydrogenase release. In RT-PCR studies, mRNAs of the P2Y(1), P2Y(2), P2Y(6), and P2X(7) receptors were detected within glomeruli and podocytes. The data indicate that extracellular nucleotides modulate podocyte function mainly by an activation of both P2Y(2) and P2Y(6) receptors.
Fischer
K G
KG
Division of Nephrology, Department of Medicine, University Hospital Freiburg, D-79106 Freiburg, Germany. fischer@med1.ukl.uni-freiburg.de
Saueressig
U
U
Jacobshagen
C
C
Wichelmann
A
A
Pavenstädt
H
H
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002461:Cell Line, Transformed; D002712:Chlorides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D005110:Extracellular Space / Q000502:physiology; D017136:Ion Transport; D007678:Kidney Glomerulus / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D009711:Nucleotides / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D018102:Receptors, Leukotriene B4; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000502:physiology*; D013498:Suramin / Q000494:pharmacology
D002712:Chlorides; C503704:Ltb4r1 protein, mouse; D009711:Nucleotides; D058919:Purinergic P2 Receptor Antagonists; D012333:RNA, Messenger; D018102:Receptors, Leukotriene B4; D018048:Receptors, Purinergic P2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D013498:Suramin; D000255:Adenosine Triphosphate; D002118:Calcium