Nucleotides mobilize intracellular calcium stores of renal proximal cells in primary culture: existence of a suramin-sensitive mechanism.
Changes of intracellular calcium concentrations [Ca2+]i were measured in primary cultured rabbit proximal convoluted tubules (PCT). A dual-excitation, digital-imaging inverted microscope was used to monitor the fura-2 fluorescence. The basal calcium level was 106 +/- 11 nM (n = 36). The stimulatory effects of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine were studied. ATP and ADP induced transient increases of [Ca2+]i (1059 +/- 115% of the resting level (n = 29), and 659 +/- 134% (n = 10), respectively) by releasing calcium from cytoplasmic stores. Adenosine had less effect (279 +/- 48% of the resting level, n = 3). In the same conditions the ATP antagonist suramin (100 microM) inhibited the action of ATP and ADP to 231 +/- 52% (n = 3), and 308 +/- 29% (n = 4) of the resting level, respectively, but did not modify that of adenosine (281 +/- 72%, n = 3). A pretreatment (500 ng/ml for 2 h at 37 degrees C) of the culture with the toxin of Bordetella pertussis completely blocked the ATP response. Our results are evidence for the presence of a functional suramin-sensitive ATP and ADP puriceptor in cultured renal proximal cells. A pertussis-toxin-sensitive G protein is linked to the transduction mechanism. This receptor is distinct from an adenosine puriceptor also found in the proximal monolayer.
Cejka
J C
JC
Département de Biologie Cellulaire et Moléculaire, CEN Saclay, Gif sur Yvette, France.
Bidet
M
M
Tauc
M
M
Poujeol
P
P
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D001886:Bordetella pertussis; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016257:Fura-2; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009711:Nucleotides / Q000494:pharmacology*; D011817:Rabbits; D013498:Suramin / Q000494:pharmacology*
D009711:Nucleotides; D000249:Adenosine Monophosphate; D013498:Suramin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2