Activation of protein kinase B/Akt and endothelial nitric oxide synthase mediates agmatine-induced endothelium-dependent relaxation

A. V R Santhanam, Shivkumar Viswanathan, Madhu Dikshit

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The ability of agmatine, formed from l-arginine by the enzyme arginine decarboxylase (ADC), to modulate vasomotor function in rat aorta was investigated in the present study. Agmatine-mediated modulation of vasomotor tone was studied in organ chambers, protein expression quantified by Western blot analysis and cyclic guanosine 5′-monophosphate (cGMP) levels measured by radioimmunoassay. Agmatine (10- 10 to 10- 3 M) produced concentration-dependent relaxations (82 ± 5%) in phenylephrine-contracted endothelium intact rat aorta. Relaxations to agmatine were diminished on denudation of endothelium and nitric oxide synthase (NOS) inhibition by l-Nω-nitro arginine or soluble guanylate cyclase inhibition by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (P < 0.001) abolished agmatine-mediated relaxations, while relaxations were insensitive to inducible NOS inhibition by 1400W. Agmatine-treated aorta demonstrated increased protein expression of phosphorylated S473-Akt and phosphorylated S1177-endothelial nitric oxide synthase (eNOS), and elevated the levels of cyclic GMP (P < 0.01). Agmatine-mediated potentiation of relaxations and elevation of cGMP levels was sensitive to phosphatidylinositol 3′-kinase inhibitor, wortmannin. Relaxations to agmatine were also affected by pre-treatment with tetraethylammonium (P < 0.01) or apamin (P < 0.05), and were not affected by charybdotoxin. Relaxations to agmatine were partially affected by pre-treatment of aortic rings with barium chloride (P < 0.05), and glybenclamide (P < 0.05). Results obtained suggest that agmatine activates protein kinase B/Akt to phosphorylate eNOS and elevate cyclic GMP levels to produce vasodilatation of aorta. Agmatine-mediated relaxations in rat aorta seems to be mediated mainly by endothelial NO-mediated activation of small conductance Ca2+-activated K+ channels, and partly by ATP-sensitive and inward rectifying K+ channels.

Original languageEnglish (US)
Pages (from-to)189-196
Number of pages8
JournalEuropean Journal of Pharmacology
Volume572
Issue number2-3
DOIs
StatePublished - Oct 31 2007

Fingerprint

Agmatine
Proto-Oncogene Proteins c-akt
Nitric Oxide Synthase Type III
Endothelium
Aorta
Guanosine Monophosphate
Cyclic GMP
Arginine
Phosphatidylinositol 3-Kinase
Charybdotoxin
Apamin
Calcium-Activated Potassium Channels
Tetraethylammonium
Glyburide
Phenylephrine
Nitric Oxide Synthase Type II
Fourier Analysis
Vasodilation
Nitric Oxide Synthase
Radioimmunoassay

Keywords

  • Akt
  • Nitric oxide synthase
  • Potassium channels
  • Rat aorta
  • Soluble guanylate cyclase
  • Vasorelaxation

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Pharmacology

Cite this

Activation of protein kinase B/Akt and endothelial nitric oxide synthase mediates agmatine-induced endothelium-dependent relaxation. / Santhanam, A. V R; Viswanathan, Shivkumar; Dikshit, Madhu.

In: European Journal of Pharmacology, Vol. 572, No. 2-3, 31.10.2007, p. 189-196.

Research output: Contribution to journalArticle

Santhanam, A. V R ; Viswanathan, Shivkumar ; Dikshit, Madhu. / Activation of protein kinase B/Akt and endothelial nitric oxide synthase mediates agmatine-induced endothelium-dependent relaxation. In: European Journal of Pharmacology. 2007 ; Vol. 572, No. 2-3. pp. 189-196.
@article{0dc6b5321ec147c2ab2515075d79eb3f,
title = "Activation of protein kinase B/Akt and endothelial nitric oxide synthase mediates agmatine-induced endothelium-dependent relaxation",
abstract = "The ability of agmatine, formed from l-arginine by the enzyme arginine decarboxylase (ADC), to modulate vasomotor function in rat aorta was investigated in the present study. Agmatine-mediated modulation of vasomotor tone was studied in organ chambers, protein expression quantified by Western blot analysis and cyclic guanosine 5′-monophosphate (cGMP) levels measured by radioimmunoassay. Agmatine (10- 10 to 10- 3 M) produced concentration-dependent relaxations (82 ± 5{\%}) in phenylephrine-contracted endothelium intact rat aorta. Relaxations to agmatine were diminished on denudation of endothelium and nitric oxide synthase (NOS) inhibition by l-Nω-nitro arginine or soluble guanylate cyclase inhibition by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (P < 0.001) abolished agmatine-mediated relaxations, while relaxations were insensitive to inducible NOS inhibition by 1400W. Agmatine-treated aorta demonstrated increased protein expression of phosphorylated S473-Akt and phosphorylated S1177-endothelial nitric oxide synthase (eNOS), and elevated the levels of cyclic GMP (P < 0.01). Agmatine-mediated potentiation of relaxations and elevation of cGMP levels was sensitive to phosphatidylinositol 3′-kinase inhibitor, wortmannin. Relaxations to agmatine were also affected by pre-treatment with tetraethylammonium (P < 0.01) or apamin (P < 0.05), and were not affected by charybdotoxin. Relaxations to agmatine were partially affected by pre-treatment of aortic rings with barium chloride (P < 0.05), and glybenclamide (P < 0.05). Results obtained suggest that agmatine activates protein kinase B/Akt to phosphorylate eNOS and elevate cyclic GMP levels to produce vasodilatation of aorta. Agmatine-mediated relaxations in rat aorta seems to be mediated mainly by endothelial NO-mediated activation of small conductance Ca2+-activated K+ channels, and partly by ATP-sensitive and inward rectifying K+ channels.",
keywords = "Akt, Nitric oxide synthase, Potassium channels, Rat aorta, Soluble guanylate cyclase, Vasorelaxation",
author = "Santhanam, {A. V R} and Shivkumar Viswanathan and Madhu Dikshit",
year = "2007",
month = "10",
day = "31",
doi = "10.1016/j.ejphar.2007.06.031",
language = "English (US)",
volume = "572",
pages = "189--196",
journal = "European Journal of Pharmacology",
issn = "0014-2999",
publisher = "Elsevier",
number = "2-3",

}

TY - JOUR

T1 - Activation of protein kinase B/Akt and endothelial nitric oxide synthase mediates agmatine-induced endothelium-dependent relaxation

AU - Santhanam, A. V R

AU - Viswanathan, Shivkumar

AU - Dikshit, Madhu

PY - 2007/10/31

Y1 - 2007/10/31

N2 - The ability of agmatine, formed from l-arginine by the enzyme arginine decarboxylase (ADC), to modulate vasomotor function in rat aorta was investigated in the present study. Agmatine-mediated modulation of vasomotor tone was studied in organ chambers, protein expression quantified by Western blot analysis and cyclic guanosine 5′-monophosphate (cGMP) levels measured by radioimmunoassay. Agmatine (10- 10 to 10- 3 M) produced concentration-dependent relaxations (82 ± 5%) in phenylephrine-contracted endothelium intact rat aorta. Relaxations to agmatine were diminished on denudation of endothelium and nitric oxide synthase (NOS) inhibition by l-Nω-nitro arginine or soluble guanylate cyclase inhibition by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (P < 0.001) abolished agmatine-mediated relaxations, while relaxations were insensitive to inducible NOS inhibition by 1400W. Agmatine-treated aorta demonstrated increased protein expression of phosphorylated S473-Akt and phosphorylated S1177-endothelial nitric oxide synthase (eNOS), and elevated the levels of cyclic GMP (P < 0.01). Agmatine-mediated potentiation of relaxations and elevation of cGMP levels was sensitive to phosphatidylinositol 3′-kinase inhibitor, wortmannin. Relaxations to agmatine were also affected by pre-treatment with tetraethylammonium (P < 0.01) or apamin (P < 0.05), and were not affected by charybdotoxin. Relaxations to agmatine were partially affected by pre-treatment of aortic rings with barium chloride (P < 0.05), and glybenclamide (P < 0.05). Results obtained suggest that agmatine activates protein kinase B/Akt to phosphorylate eNOS and elevate cyclic GMP levels to produce vasodilatation of aorta. Agmatine-mediated relaxations in rat aorta seems to be mediated mainly by endothelial NO-mediated activation of small conductance Ca2+-activated K+ channels, and partly by ATP-sensitive and inward rectifying K+ channels.

AB - The ability of agmatine, formed from l-arginine by the enzyme arginine decarboxylase (ADC), to modulate vasomotor function in rat aorta was investigated in the present study. Agmatine-mediated modulation of vasomotor tone was studied in organ chambers, protein expression quantified by Western blot analysis and cyclic guanosine 5′-monophosphate (cGMP) levels measured by radioimmunoassay. Agmatine (10- 10 to 10- 3 M) produced concentration-dependent relaxations (82 ± 5%) in phenylephrine-contracted endothelium intact rat aorta. Relaxations to agmatine were diminished on denudation of endothelium and nitric oxide synthase (NOS) inhibition by l-Nω-nitro arginine or soluble guanylate cyclase inhibition by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (P < 0.001) abolished agmatine-mediated relaxations, while relaxations were insensitive to inducible NOS inhibition by 1400W. Agmatine-treated aorta demonstrated increased protein expression of phosphorylated S473-Akt and phosphorylated S1177-endothelial nitric oxide synthase (eNOS), and elevated the levels of cyclic GMP (P < 0.01). Agmatine-mediated potentiation of relaxations and elevation of cGMP levels was sensitive to phosphatidylinositol 3′-kinase inhibitor, wortmannin. Relaxations to agmatine were also affected by pre-treatment with tetraethylammonium (P < 0.01) or apamin (P < 0.05), and were not affected by charybdotoxin. Relaxations to agmatine were partially affected by pre-treatment of aortic rings with barium chloride (P < 0.05), and glybenclamide (P < 0.05). Results obtained suggest that agmatine activates protein kinase B/Akt to phosphorylate eNOS and elevate cyclic GMP levels to produce vasodilatation of aorta. Agmatine-mediated relaxations in rat aorta seems to be mediated mainly by endothelial NO-mediated activation of small conductance Ca2+-activated K+ channels, and partly by ATP-sensitive and inward rectifying K+ channels.

KW - Akt

KW - Nitric oxide synthase

KW - Potassium channels

KW - Rat aorta

KW - Soluble guanylate cyclase

KW - Vasorelaxation

UR - http://www.scopus.com/inward/record.url?scp=34548800397&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34548800397&partnerID=8YFLogxK

U2 - 10.1016/j.ejphar.2007.06.031

DO - 10.1016/j.ejphar.2007.06.031

M3 - Article

VL - 572

SP - 189

EP - 196

JO - European Journal of Pharmacology

JF - European Journal of Pharmacology

SN - 0014-2999

IS - 2-3

ER -