Natriuretic peptides and diadenosine polyphosphates modulate pH regulation of rat mesangial cells.
Modulation of cell proliferation has often been thought to be connected to changes in the activity of pH-regulatory transporters and consequently intracellular pH (pH(i)). The influence of natriuretic peptides, diadenosine polyphosphates, adenosine and ATP as well as platelet-derived growth factor (PDGF) on pH(i) regulation of cultured rat mesangial cells was examined with the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. The inhibitors of Na(+)/H(+) exchange, amiloride and HOE694, blocked pH(i) recovery completely in the absence of and by approximately 50% in the presence of HCO(3)(-)/CO(2). Natriuretic peptides (ANP, BNP, CNP, urodilatin) completely inhibited pH(i) recovery in the absence of and by approximately 40% in the presence of HCO(3)(-)/CO(2). These effects were abolished by the cGMP-dependent protein kinase inhibitor KT5823. Diadenosine polyphosphates (Ap3A-Ap6A), ATP and adenosine also inhibited pH(i) recovery completely in the absence of and partially (30-40%) in the presence of HCO(3)(-)/ CO(2). The effect of adenosine was abolished in the presence of the cAMP-dependent protein kinase inhibitor KT5720, and that of Ap5A by the protein kinase C inhibitor calphostin C. PDGF activated acid extrusion in these cells by approximately 40%. From the four cloned isoforms of the Na(+)/H(+) exchanger in the rat, only transcripts of NHE-1 were found in these mesangial cell cultures using RT-PCR analysis. These data suggest that in these rat mesangial cells the Na(+)/H(+) exchanger, specifically the NHE-1 isoform, accounts for around 50% of pH(i) recovery from an acid load under physiological conditions, and that Na(+)/H(+) exchange stimulated by acidification can be inhibited by activation of PKG, PKA, and PKC and stimulated by PDGF after acute exposition to these agonists.
Schulte
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EA
Westfälische Wilhelms-Universität, Medizinische Poliklinik, Experimentelle Nephrologie, Münster, Deutschland. eberhard.schlatter@uni-muenster.de
Hohendahl
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Stegemann
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Hirsch
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JR
Saleh
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Schlatter
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D000227:Adenine Nucleotides / Q000494:pharmacology*; D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002227:Carbazoles; D002478:Cells, Cultured; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D005920:Glomerular Mesangium / Q000187:drug effects / Q000502:physiology*; D006146:Guanidines / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*; D013450:Sulfones / Q000494:pharmacology
D000227:Adenine Nucleotides; D000470:Alkaloids; D002227:Carbazoles; D015226:Dinucleoside Phosphates; D006146:Guanidines; D007211:Indoles; D010982:Platelet-Derived Growth Factor; D011758:Pyrroles; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C069139:growth factor-activatable Na-H exchanger NHE-1; C073601:KT 5823; C074107:3-methylsulfonyl-4-piperidinobenzoyl guanidine; C057416:KT 5720; D009320:Atrial Natriuretic Factor; D000255:Adenosine Triphosphate; D000241:Adenosine