ATP inhibits Mg2+ uptake in MDCT cells via P2X purinoceptors

greedy — Tue, 15 Sep 2009 00:09:22 +0000

Dai LJ, Kand HS, Kerstan D, Ritchie G, and Quamme GA: ATP inhibits Mg²⁺ uptake in MDCT cells via P2X purinoceptors. American Journal of Physiology 281:F833-F840, 2001.

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Abstract Nucleotides have diverse effects on water and electrolyte reabsorption within the distal tubule of the nephron. As the distal tubule is important in control of renal Mg21 balance, we determined the effects of ATP on cellular Mg21 uptake in this segment. The effects of ATP on immortalized mouse distal convoluted tubule (MDCT) cells were studied by measuring Mg21 uptake with fluorescence techniques. The mean basal Mg21 uptake rate was 165 6 6 nM/s. ATP inhibited basal Mg21 uptake and hormone-stimulated Mg21 entry by 40%. Both P2X (P2X1– P2X5 subtypes) and P2Y2 receptor subtypes were identified in MDCT cells using differential RT-PCR. Activation of both receptor subtypes with selective agonists increased intracellular Ca21 concentration, P2X purinoceptors by ionotropicgated channels, and P2Y receptors via G protein-mediated intracellular Ca21 release. The more relatively selective P2X agonists [b,g-methylene ATP (b,g-Me-ATP) and 29- and -39- O-(4-benzoyl-benzoyl)-ATP] inhibited arginine vasopressin (AVP)- and parathyroid hormone (PTH)-mediated Mg21 uptake whereas agonists more selective for P2Y purinoceptors (UTP, ADP, and 2-methylthio-ATP) were without effect. Removal of extracellular Ca21 diminished b,g-Me-ATP-mediated increase in intracellular Ca21 and inhibition of AVPstimulated Mg21 entry. We conclude from this information that ATP inhibited Mg21 uptake in MDCT cells through P2X purinoceptors expressed in this distal convoluted tubule cell line.

Nucleotides have

diverse effects on water and electrolyte reabsorption within

the distal tubule of the nephron. As the distal tubule is

important in control of renal Mg21 balance, we determined

the effects of ATP on cellular Mg21 uptake in this segment.

The effects of ATP on immortalized mouse distal convoluted

tubule (MDCT) cells were studied by measuring Mg21 uptake

with fluorescence techniques. The mean basal Mg21 uptake

rate was 165 6 6 nM/s. ATP inhibited basal Mg21 uptake and

hormone-stimulated Mg21 entry by 40%. Both P2X (P2X1–

P2X5 subtypes) and P2Y2 receptor subtypes were identified

in MDCT cells using differential RT-PCR. Activation of both

receptor subtypes with selective agonists increased intracellular

Ca21 concentration, P2X purinoceptors by ionotropicgated

channels, and P2Y receptors via G protein-mediated

intracellular Ca21 release. The more relatively selective P2X

agonists [b,g-methylene ATP (b,g-Me-ATP) and 29- and -39-

O-(4-benzoyl-benzoyl)-ATP] inhibited arginine vasopressin

(AVP)- and parathyroid hormone (PTH)-mediated Mg21 uptake

whereas agonists more selective for P2Y purinoceptors

(UTP, ADP, and 2-methylthio-ATP) were without effect. Removal

of extracellular Ca21 diminished b,g-Me-ATP-mediated

increase in intracellular Ca21 and inhibition of AVPstimulated

Mg21 entry. We conclude from this information

that ATP inhibited Mg21 uptake in MDCT cells through P2X

purinoceptors expressed in this distal convoluted tubule cell

line.

intracellular magnesium, fluorescence; adenosine triphosphate

Dr. Long Jun Dai » adenosine triphosphate

ATP inhibits Mg2+ uptake in MDCT cells via P2X purinoceptors