Agmatine inhibits arginine vasopressin-stimulated urea transport in the rat inner medullary collecting duct

Alexander J. Rouch, Luúcia H. Kudo

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Background. Agmatine, a putative endogenous ligand for imidazoline receptors, induces numerous biological effects. The agonist clonidine binds to alpha-2 (α2) adrenoceptors and imidazoline receptors, and inhibits arginine vasopressin (AVP)-stimulated urea permeability (Pu) in the rat inner medullary collecting duct (IMCD). Dexmedetomidine, a selective α2 agonist, does not inhibit AVP-stimulated Pu. This study was conducted to determine if agmatine affects Pu in the rat IMCD)and to investigate the possibility of an imidazoline-mediated mechanism. Methods. The isolated-perfused tubule technique was used to measure Pu in IMCDs from Wistar rats. AVP at 220 pmol/L or 8-chlorophenylthio cyclic adenosine monophosphate (8CPT cAMP) was used to stimulate Pu. Agmatine and other agents were added to the bath. Results. Agmatine at 1 μmol/L inhibited AVP-stimulated Pu by 50%. Agmatine-induced inhibition could not be separated completely from inhibition produced by the non-imidazoline, catecholamine epinephrine. Of three antagonists selective for α2 adrenoceptors (rauwolscine, yohimbine, and RX821002), only rauwolscine reversed inhibition, whereas each of the three imidazoline-selective antagonists tested (atipamezole, idazoxan, and BU239) produced a significant reversal. Agmatine did not affect basal Pu or inhibit 8CPTcAMP-stimulated Pu. Conclusion. Our results indicate that agmatine inhibits AVP stimulated Pu by a cAMP-dependent mechanism. Imidazoline receptors are probably not involved. The possibility exists of an unknown agmatine-selective receptor modulating urea transport in the rat IMCD.

Original languageEnglish
Pages (from-to)2101-2108
Number of pages8
JournalKidney International
Volume62
Issue number6
DOIs
StatePublished - 1 Jan 2002

Fingerprint

Agmatine
Arginine Vasopressin
Urea
Imidazoline Receptors
Yohimbine
Imidazolines
Adrenergic Receptors
Idazoxan
Dexmedetomidine
Clonidine
Baths
Cyclic AMP
Epinephrine
Catecholamines
Wistar Rats
Permeability
Ligands

Keywords

  • AVP
  • Cyclic AMP
  • IMCD
  • Imidazoline receptor
  • Urea permeability
  • α adrenoceptors

Cite this

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title = "Agmatine inhibits arginine vasopressin-stimulated urea transport in the rat inner medullary collecting duct",
abstract = "Background. Agmatine, a putative endogenous ligand for imidazoline receptors, induces numerous biological effects. The agonist clonidine binds to alpha-2 (α2) adrenoceptors and imidazoline receptors, and inhibits arginine vasopressin (AVP)-stimulated urea permeability (Pu) in the rat inner medullary collecting duct (IMCD). Dexmedetomidine, a selective α2 agonist, does not inhibit AVP-stimulated Pu. This study was conducted to determine if agmatine affects Pu in the rat IMCD)and to investigate the possibility of an imidazoline-mediated mechanism. Methods. The isolated-perfused tubule technique was used to measure Pu in IMCDs from Wistar rats. AVP at 220 pmol/L or 8-chlorophenylthio cyclic adenosine monophosphate (8CPT cAMP) was used to stimulate Pu. Agmatine and other agents were added to the bath. Results. Agmatine at 1 μmol/L inhibited AVP-stimulated Pu by 50{\%}. Agmatine-induced inhibition could not be separated completely from inhibition produced by the non-imidazoline, catecholamine epinephrine. Of three antagonists selective for α2 adrenoceptors (rauwolscine, yohimbine, and RX821002), only rauwolscine reversed inhibition, whereas each of the three imidazoline-selective antagonists tested (atipamezole, idazoxan, and BU239) produced a significant reversal. Agmatine did not affect basal Pu or inhibit 8CPTcAMP-stimulated Pu. Conclusion. Our results indicate that agmatine inhibits AVP stimulated Pu by a cAMP-dependent mechanism. Imidazoline receptors are probably not involved. The possibility exists of an unknown agmatine-selective receptor modulating urea transport in the rat IMCD.",
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author = "Rouch, {Alexander J.} and Kudo, {Lu{\'u}cia H.}",
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Agmatine inhibits arginine vasopressin-stimulated urea transport in the rat inner medullary collecting duct. / Rouch, Alexander J.; Kudo, Luúcia H.

In: Kidney International, Vol. 62, No. 6, 01.01.2002, p. 2101-2108.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Agmatine inhibits arginine vasopressin-stimulated urea transport in the rat inner medullary collecting duct

AU - Rouch, Alexander J.

AU - Kudo, Luúcia H.

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N2 - Background. Agmatine, a putative endogenous ligand for imidazoline receptors, induces numerous biological effects. The agonist clonidine binds to alpha-2 (α2) adrenoceptors and imidazoline receptors, and inhibits arginine vasopressin (AVP)-stimulated urea permeability (Pu) in the rat inner medullary collecting duct (IMCD). Dexmedetomidine, a selective α2 agonist, does not inhibit AVP-stimulated Pu. This study was conducted to determine if agmatine affects Pu in the rat IMCD)and to investigate the possibility of an imidazoline-mediated mechanism. Methods. The isolated-perfused tubule technique was used to measure Pu in IMCDs from Wistar rats. AVP at 220 pmol/L or 8-chlorophenylthio cyclic adenosine monophosphate (8CPT cAMP) was used to stimulate Pu. Agmatine and other agents were added to the bath. Results. Agmatine at 1 μmol/L inhibited AVP-stimulated Pu by 50%. Agmatine-induced inhibition could not be separated completely from inhibition produced by the non-imidazoline, catecholamine epinephrine. Of three antagonists selective for α2 adrenoceptors (rauwolscine, yohimbine, and RX821002), only rauwolscine reversed inhibition, whereas each of the three imidazoline-selective antagonists tested (atipamezole, idazoxan, and BU239) produced a significant reversal. Agmatine did not affect basal Pu or inhibit 8CPTcAMP-stimulated Pu. Conclusion. Our results indicate that agmatine inhibits AVP stimulated Pu by a cAMP-dependent mechanism. Imidazoline receptors are probably not involved. The possibility exists of an unknown agmatine-selective receptor modulating urea transport in the rat IMCD.

AB - Background. Agmatine, a putative endogenous ligand for imidazoline receptors, induces numerous biological effects. The agonist clonidine binds to alpha-2 (α2) adrenoceptors and imidazoline receptors, and inhibits arginine vasopressin (AVP)-stimulated urea permeability (Pu) in the rat inner medullary collecting duct (IMCD). Dexmedetomidine, a selective α2 agonist, does not inhibit AVP-stimulated Pu. This study was conducted to determine if agmatine affects Pu in the rat IMCD)and to investigate the possibility of an imidazoline-mediated mechanism. Methods. The isolated-perfused tubule technique was used to measure Pu in IMCDs from Wistar rats. AVP at 220 pmol/L or 8-chlorophenylthio cyclic adenosine monophosphate (8CPT cAMP) was used to stimulate Pu. Agmatine and other agents were added to the bath. Results. Agmatine at 1 μmol/L inhibited AVP-stimulated Pu by 50%. Agmatine-induced inhibition could not be separated completely from inhibition produced by the non-imidazoline, catecholamine epinephrine. Of three antagonists selective for α2 adrenoceptors (rauwolscine, yohimbine, and RX821002), only rauwolscine reversed inhibition, whereas each of the three imidazoline-selective antagonists tested (atipamezole, idazoxan, and BU239) produced a significant reversal. Agmatine did not affect basal Pu or inhibit 8CPTcAMP-stimulated Pu. Conclusion. Our results indicate that agmatine inhibits AVP stimulated Pu by a cAMP-dependent mechanism. Imidazoline receptors are probably not involved. The possibility exists of an unknown agmatine-selective receptor modulating urea transport in the rat IMCD.

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