Rapid functional upregulation of vasocontractile endothelin ET_B receptors in rat coronary arteries

TY - JOUR

T1 - Rapid functional upregulation of vasocontractile endothelin ETB receptors in rat coronary arteries

AU - Skovsted, Gry Freja

AU - Pedersen, Anne Fog

AU - Larsen, Rikke

AU - Sheykhzade, Majid

AU - Edvinsson, Lars

N1 - Copyright © 2012 Elsevier Inc. All rights reserved.

PY - 2012/10/15

Y1 - 2012/10/15

N2 - Aims: Endothelin ETB receptors mediate under normal physiological conditions vasorelaxation in coronary arteries. However, vasocontractile ETB receptors appear in coronary arteries of ischemic heart disease patients. Interestingly, organ culture of isolated coronary arteries also induces upregulation of vasocontractile ETB receptors. This study examines the early time course and mechanism behind upregulation of contractile ETB receptors in isolated rat coronary arteries during short-term organ culture. Main methods: Coronary artery segments were mounted in wire-myographs and incubated in physiological saline solution. Contractions were measured after exposure to the specific ETB receptor agonist Sarafotoxin 6c (S6c) and the endogenous agonists endothelin-1 and endothelin-3. Protein localization and levels of ETB and phosphorylated- extracellular-signal-regulated-kinase-1/2 (ERK1/2) were examined by immunohistochemistry. Key findings: Fresh arteries showed negligible vasoconstriction to S6c. However, incubation for only 4 and 7 h increased S6c contractions two- and seven-fold, respectively. Furthermore, 7 h incubation enhanced vasocontractile responses to endothelin-3 and increased ETB receptor density in vascular smooth muscle cells. ERK1/2 was activated rapidly after start of incubation. Moreover, incubation with either the transcriptional inhibitor actinomycin D or the mitogen-activated-protein kinase kinase 1/2 (MEK1/2) inhibitor U0126 attenuated contractile ETB receptor upregulation. U0126 attenuated ETB receptor protein levels after 24 h of incubation. Significance: Coronary arteries rapidly upregulate vasocontractile ETB receptors during organ culture via transcriptional mechanisms and MEK-ERK1/2 signalling. This model may mimic the mechanisms seen in ischemic conditions. Furthermore, these findings have important experimental implications in tissue bath experiments lasting for more than 4 h.

AB - Aims: Endothelin ETB receptors mediate under normal physiological conditions vasorelaxation in coronary arteries. However, vasocontractile ETB receptors appear in coronary arteries of ischemic heart disease patients. Interestingly, organ culture of isolated coronary arteries also induces upregulation of vasocontractile ETB receptors. This study examines the early time course and mechanism behind upregulation of contractile ETB receptors in isolated rat coronary arteries during short-term organ culture. Main methods: Coronary artery segments were mounted in wire-myographs and incubated in physiological saline solution. Contractions were measured after exposure to the specific ETB receptor agonist Sarafotoxin 6c (S6c) and the endogenous agonists endothelin-1 and endothelin-3. Protein localization and levels of ETB and phosphorylated- extracellular-signal-regulated-kinase-1/2 (ERK1/2) were examined by immunohistochemistry. Key findings: Fresh arteries showed negligible vasoconstriction to S6c. However, incubation for only 4 and 7 h increased S6c contractions two- and seven-fold, respectively. Furthermore, 7 h incubation enhanced vasocontractile responses to endothelin-3 and increased ETB receptor density in vascular smooth muscle cells. ERK1/2 was activated rapidly after start of incubation. Moreover, incubation with either the transcriptional inhibitor actinomycin D or the mitogen-activated-protein kinase kinase 1/2 (MEK1/2) inhibitor U0126 attenuated contractile ETB receptor upregulation. U0126 attenuated ETB receptor protein levels after 24 h of incubation. Significance: Coronary arteries rapidly upregulate vasocontractile ETB receptors during organ culture via transcriptional mechanisms and MEK-ERK1/2 signalling. This model may mimic the mechanisms seen in ischemic conditions. Furthermore, these findings have important experimental implications in tissue bath experiments lasting for more than 4 h.

U2 - 10.1016/j.lfs.2012.02.009

DO - 10.1016/j.lfs.2012.02.009

M3 - Journal article

C2 - 22391414

SN - 2042-4329

VL - 91

SP - 593

EP - 599

JO - Life Sciences

JF - Life Sciences

IS - 13-14

ER -