Abstract
Regulation of plasma membrane ion transport by endogenous purinergic receptors was assessed in a distal renal (A6) cell line. Nucleotide analogues stimulated Na-K-Cl cotransport activity with relative potencies of ATP > UTP > ATPγS > 2-methylthio-ATP = α,β-methylene ATP. Activation of nucleotide receptors with extracellular ATP and nucleotide analogues increased intracellular calcium concentration ([Ca2+]i) primarily by release of intracellular calcium stores, with relative potency of agonists similar to that seen for stimulation of Na-K-Cl cotransport. Neither the change in [Ca2+]i nor the stimulation of cotransport was abolished by the adenosine receptor antagonist 8-{4-[N-(2-aminoethyl)carbamoylmethoxy]-phenyl}-1,3-dipropylxanthine (XAC). In contrast to the adenosine A2 receptor agonist 5′-N-ethylcarboxamidoadenosine, nucleotide analogues had no discernible effect on cytosolic adenosine 3′,5′-cyclic monophosphate levels or adenylyl cyclase activity. To address possible mechanisms for stimulation of Na-K-Cl cotransport by the nucleotide receptor, 125I efflux and patch-clamp studies were used to measure chloride secretion. ATP and ionomycin markedly enhanced 125I efflux and whole cell currents, consistent with activation of chloride conductance pathways. Diphenylamine-2-carboxylate, a chloride channel blocker, eliminated the effects of ionomycin, forskolin, adenosine, and ATP on Na-K-Cl cotransport. This study demonstrates that nucleotide receptors in this model of renal epithelium initiate distinct regulation of Na-K-Cl cotransport. Nucleotide receptors may effect their responses through primary activation of membrane chloride channels.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Renal Fluid and Electrolyte Physiology |
| Volume | 264 |
| Issue number | 5 33-5 |
| State | Published - May 1993 |
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Keywords
- A6 cells
- Chloride channels
- Furosemide
- Purinergic receptors
ASJC Scopus subject areas
- Physiology
Cite this
Nucleotide receptors regulate membrane ion transport in renal epithelial cells. / Middleton, John P.; Mangel, Allen W.; Basavappa, Srisaila; Fitz, J. Gregory.
In: American Journal of Physiology - Renal Fluid and Electrolyte Physiology, Vol. 264, No. 5 33-5, 05.1993.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Nucleotide receptors regulate membrane ion transport in renal epithelial cells
AU - Middleton, John P.
AU - Mangel, Allen W.
AU - Basavappa, Srisaila
AU - Fitz, J. Gregory
PY - 1993/5
Y1 - 1993/5
N2 - Regulation of plasma membrane ion transport by endogenous purinergic receptors was assessed in a distal renal (A6) cell line. Nucleotide analogues stimulated Na-K-Cl cotransport activity with relative potencies of ATP > UTP > ATPγS > 2-methylthio-ATP = α,β-methylene ATP. Activation of nucleotide receptors with extracellular ATP and nucleotide analogues increased intracellular calcium concentration ([Ca2+]i) primarily by release of intracellular calcium stores, with relative potency of agonists similar to that seen for stimulation of Na-K-Cl cotransport. Neither the change in [Ca2+]i nor the stimulation of cotransport was abolished by the adenosine receptor antagonist 8-{4-[N-(2-aminoethyl)carbamoylmethoxy]-phenyl}-1,3-dipropylxanthine (XAC). In contrast to the adenosine A2 receptor agonist 5′-N-ethylcarboxamidoadenosine, nucleotide analogues had no discernible effect on cytosolic adenosine 3′,5′-cyclic monophosphate levels or adenylyl cyclase activity. To address possible mechanisms for stimulation of Na-K-Cl cotransport by the nucleotide receptor, 125I efflux and patch-clamp studies were used to measure chloride secretion. ATP and ionomycin markedly enhanced 125I efflux and whole cell currents, consistent with activation of chloride conductance pathways. Diphenylamine-2-carboxylate, a chloride channel blocker, eliminated the effects of ionomycin, forskolin, adenosine, and ATP on Na-K-Cl cotransport. This study demonstrates that nucleotide receptors in this model of renal epithelium initiate distinct regulation of Na-K-Cl cotransport. Nucleotide receptors may effect their responses through primary activation of membrane chloride channels.
AB - Regulation of plasma membrane ion transport by endogenous purinergic receptors was assessed in a distal renal (A6) cell line. Nucleotide analogues stimulated Na-K-Cl cotransport activity with relative potencies of ATP > UTP > ATPγS > 2-methylthio-ATP = α,β-methylene ATP. Activation of nucleotide receptors with extracellular ATP and nucleotide analogues increased intracellular calcium concentration ([Ca2+]i) primarily by release of intracellular calcium stores, with relative potency of agonists similar to that seen for stimulation of Na-K-Cl cotransport. Neither the change in [Ca2+]i nor the stimulation of cotransport was abolished by the adenosine receptor antagonist 8-{4-[N-(2-aminoethyl)carbamoylmethoxy]-phenyl}-1,3-dipropylxanthine (XAC). In contrast to the adenosine A2 receptor agonist 5′-N-ethylcarboxamidoadenosine, nucleotide analogues had no discernible effect on cytosolic adenosine 3′,5′-cyclic monophosphate levels or adenylyl cyclase activity. To address possible mechanisms for stimulation of Na-K-Cl cotransport by the nucleotide receptor, 125I efflux and patch-clamp studies were used to measure chloride secretion. ATP and ionomycin markedly enhanced 125I efflux and whole cell currents, consistent with activation of chloride conductance pathways. Diphenylamine-2-carboxylate, a chloride channel blocker, eliminated the effects of ionomycin, forskolin, adenosine, and ATP on Na-K-Cl cotransport. This study demonstrates that nucleotide receptors in this model of renal epithelium initiate distinct regulation of Na-K-Cl cotransport. Nucleotide receptors may effect their responses through primary activation of membrane chloride channels.
KW - A6 cells
KW - Chloride channels
KW - Furosemide
KW - Purinergic receptors
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M3 - Article
VL - 264
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
SN - 0363-6135
IS - 5 33-5
ER -