Angiotensin type 2 receptors in the intermediolateral cell column of the spinal cord: Negative regulation of sympathetic nerve activity and blood pressure

Jie Chao, Juan Gao, Karma Jaya K Parbhu, Lie Gao

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Background Our previous study demonstrated that AT2R in brainstem nuclei participated in the regulation of sympathetic outflow and cardiovascular function. However, the functional significance of AT2R in the intermediolateral cell column (IML) of the thoracic spinal cord in normal rats remains elusive. We hypothesized that AT2R activation in the IML exerts a sympatho-inhibitory effect. Methods and results Using Western-blot analysis, immunohistochemical staining and quantitative real-time PCR, both AT1R and AT2R expressions were detected in the spinal cord. The highest AT2R protein expression was found in the IML, while AT1R expression didn't display regional differences within the gray matter. Microinjection of Ang II into the IML dose-dependently elevated mean blood pressure (MAP, employing a transducer-tipped catheter) and renal sympathetic nerve activity (RSNA, using a pair of platinum-iridium recording electrodes), which were completely abolished by Losartan, and attenuated by TEMPOL and apocynin. Activation of AT2R in the IML with CGP42112 evoked hypotension (ΔMAP: - 21 ± 4 mm Hg) and sympatho-inhibition (RSNA: 73 ± 3% of baseline), which were completely abolished by PD123319 and l-NAME. Blockade of AT2R in the IML with PD123319 significantly increased MAP (11 ± 1 mm Hg) and sympathetic nerve activity (RSNA: 133 ± 13% of baseline). Moreover, PD123319 significantly enhanced the Ang II induced pressor response. Furthermore, in isolated IML neurons, CGP42112 treatment augmented potassium current and decreased resting membrane potential by employing whole-cell patch clamp. Conclusion In the normal condition, AT2R in the IML tonically inhibits sympathetic activity through an NO/NOS dependent pathway and subsequent potassium channel activation.

Original languageEnglish (US)
Pages (from-to)4046-4055
Number of pages10
JournalInternational Journal of Cardiology
Volume168
Issue number4
DOIs
StatePublished - Oct 9 2013

Fingerprint

Angiotensin Type 2 Receptor
Spinal Cord
Blood Pressure
Iridium
Losartan
Potassium Channels
Microinjections
Platinum
Transducers
Membrane Potentials
Hypotension
Brain Stem
Real-Time Polymerase Chain Reaction
Potassium
Electrodes
Thorax
Catheters
Western Blotting
Staining and Labeling
Kidney

Keywords

  • Angiotensin type 1 receptor
  • Angiotensin type 2 receptor
  • Arterial blood pressure
  • Intermediolateral cell column
  • Renal sympathetic nerve activity

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Medicine(all)

Cite this

Angiotensin type 2 receptors in the intermediolateral cell column of the spinal cord : Negative regulation of sympathetic nerve activity and blood pressure. / Chao, Jie; Gao, Juan; Parbhu, Karma Jaya K; Gao, Lie.

In: International Journal of Cardiology, Vol. 168, No. 4, 09.10.2013, p. 4046-4055.

Research output: Contribution to journalArticle

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abstract = "Background Our previous study demonstrated that AT2R in brainstem nuclei participated in the regulation of sympathetic outflow and cardiovascular function. However, the functional significance of AT2R in the intermediolateral cell column (IML) of the thoracic spinal cord in normal rats remains elusive. We hypothesized that AT2R activation in the IML exerts a sympatho-inhibitory effect. Methods and results Using Western-blot analysis, immunohistochemical staining and quantitative real-time PCR, both AT1R and AT2R expressions were detected in the spinal cord. The highest AT2R protein expression was found in the IML, while AT1R expression didn't display regional differences within the gray matter. Microinjection of Ang II into the IML dose-dependently elevated mean blood pressure (MAP, employing a transducer-tipped catheter) and renal sympathetic nerve activity (RSNA, using a pair of platinum-iridium recording electrodes), which were completely abolished by Losartan, and attenuated by TEMPOL and apocynin. Activation of AT2R in the IML with CGP42112 evoked hypotension (ΔMAP: - 21 ± 4 mm Hg) and sympatho-inhibition (RSNA: 73 ± 3{\%} of baseline), which were completely abolished by PD123319 and l-NAME. Blockade of AT2R in the IML with PD123319 significantly increased MAP (11 ± 1 mm Hg) and sympathetic nerve activity (RSNA: 133 ± 13{\%} of baseline). Moreover, PD123319 significantly enhanced the Ang II induced pressor response. Furthermore, in isolated IML neurons, CGP42112 treatment augmented potassium current and decreased resting membrane potential by employing whole-cell patch clamp. Conclusion In the normal condition, AT2R in the IML tonically inhibits sympathetic activity through an NO/NOS dependent pathway and subsequent potassium channel activation.",
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author = "Jie Chao and Juan Gao and Parbhu, {Karma Jaya K} and Lie Gao",
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T2 - Negative regulation of sympathetic nerve activity and blood pressure

AU - Chao, Jie

AU - Gao, Juan

AU - Parbhu, Karma Jaya K

AU - Gao, Lie

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N2 - Background Our previous study demonstrated that AT2R in brainstem nuclei participated in the regulation of sympathetic outflow and cardiovascular function. However, the functional significance of AT2R in the intermediolateral cell column (IML) of the thoracic spinal cord in normal rats remains elusive. We hypothesized that AT2R activation in the IML exerts a sympatho-inhibitory effect. Methods and results Using Western-blot analysis, immunohistochemical staining and quantitative real-time PCR, both AT1R and AT2R expressions were detected in the spinal cord. The highest AT2R protein expression was found in the IML, while AT1R expression didn't display regional differences within the gray matter. Microinjection of Ang II into the IML dose-dependently elevated mean blood pressure (MAP, employing a transducer-tipped catheter) and renal sympathetic nerve activity (RSNA, using a pair of platinum-iridium recording electrodes), which were completely abolished by Losartan, and attenuated by TEMPOL and apocynin. Activation of AT2R in the IML with CGP42112 evoked hypotension (ΔMAP: - 21 ± 4 mm Hg) and sympatho-inhibition (RSNA: 73 ± 3% of baseline), which were completely abolished by PD123319 and l-NAME. Blockade of AT2R in the IML with PD123319 significantly increased MAP (11 ± 1 mm Hg) and sympathetic nerve activity (RSNA: 133 ± 13% of baseline). Moreover, PD123319 significantly enhanced the Ang II induced pressor response. Furthermore, in isolated IML neurons, CGP42112 treatment augmented potassium current and decreased resting membrane potential by employing whole-cell patch clamp. Conclusion In the normal condition, AT2R in the IML tonically inhibits sympathetic activity through an NO/NOS dependent pathway and subsequent potassium channel activation.

AB - Background Our previous study demonstrated that AT2R in brainstem nuclei participated in the regulation of sympathetic outflow and cardiovascular function. However, the functional significance of AT2R in the intermediolateral cell column (IML) of the thoracic spinal cord in normal rats remains elusive. We hypothesized that AT2R activation in the IML exerts a sympatho-inhibitory effect. Methods and results Using Western-blot analysis, immunohistochemical staining and quantitative real-time PCR, both AT1R and AT2R expressions were detected in the spinal cord. The highest AT2R protein expression was found in the IML, while AT1R expression didn't display regional differences within the gray matter. Microinjection of Ang II into the IML dose-dependently elevated mean blood pressure (MAP, employing a transducer-tipped catheter) and renal sympathetic nerve activity (RSNA, using a pair of platinum-iridium recording electrodes), which were completely abolished by Losartan, and attenuated by TEMPOL and apocynin. Activation of AT2R in the IML with CGP42112 evoked hypotension (ΔMAP: - 21 ± 4 mm Hg) and sympatho-inhibition (RSNA: 73 ± 3% of baseline), which were completely abolished by PD123319 and l-NAME. Blockade of AT2R in the IML with PD123319 significantly increased MAP (11 ± 1 mm Hg) and sympathetic nerve activity (RSNA: 133 ± 13% of baseline). Moreover, PD123319 significantly enhanced the Ang II induced pressor response. Furthermore, in isolated IML neurons, CGP42112 treatment augmented potassium current and decreased resting membrane potential by employing whole-cell patch clamp. Conclusion In the normal condition, AT2R in the IML tonically inhibits sympathetic activity through an NO/NOS dependent pathway and subsequent potassium channel activation.

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KW - Renal sympathetic nerve activity

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