NMDA antagonists attenuate hypertension induced by carotid clamping in the rostral ventrolateral medulla of rats

Kao, M. C.; Lee, H.K.; Chai, C. Y.; Wang, Yun

doi:10.1016/0006-8993(91)90602-r

Cited by 23 publications

(8 citation statements)

References 22 publications

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“…In addition to its role in regulating blood pressure, the RVLM is an essential component of several cardiovascular reflexes, including the central ischemia reflex (Dampney and Moon, 1980;Kao et al, 1991), the exercise pressor reflex (Stornetta et al, 1989;Hand et al, 1997;Ally, 1998;Williams et al, 2000;Ally et al, 2002), and the diving response (McCulloch et al, 1999). The Bötzinger complex is also at these levels of the medulla (Kalia et al, 1979), where bulbospinal expiratory neurons are found (Lipski and merrill, 1980;Tian et al, 1998Tian et al, , 1999Schreihofer et al, 1999).…”

Section: Caudal and Rostral Ventrolateral Medullamentioning

confidence: 99%

Defining projections from the caudal pressor area of the caudal ventrolateral medulla

Sun

Panneton

2004

J. Comp. Neurol.

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We previously defined a functional area in the caudal medulla oblongata that elicits an increase in arterial pressure when stimulated (Sun and Panneton [2002] Am. J. Physiol. 283:R768-R778). In the present study, anterograde and retrograde tracing techniques were used to investigate the projections of this caudal pressor area (CPA) to the medulla and pons. Injections of biotinylated dextran amine into the CPA resulted in numerous labeled fibers with varicosities in the ipsilateral subnucleus reticularis dorsalis, commissural subnucleus of the nucleus tractus solitarii, lateral medulla, medial facial nucleus, A5 area, lateral vestibular nucleus, and internal lateral subnucleus of the parabrachial complex. Sparser projections were found ipsilaterally in the pressor and depressor areas of the medulla and the spinal trigeminal nucleus and contralaterally in the CPA. Injections of the retrograde tracer Fluoro-Gold into these areas labeled neurons in the CPA as well as the nearby medullary dorsal horn and reticular formation. However, we conclude that the CPA projects preferentially to the subnucleus reticularis dorsalis, commissural nucleus tractus solitarii, lateral medulla, A5 area, and internal lateral parabrachial nucleus. Weaker projections were seen to the CVLM and RVLM and to the contralateral CPA. The projection to the facial nucleus arises from nearby reticular neurons, whereas projections to the vestibular nucleus arise from the lateral reticular nucleus. Labeled neurons in the CPA consisted mostly of small bipolar and some triangular neurons. The projection to the CVLM, or to A5 area, may provide for the increase in arterial pressure with CPA stimulation. However, most of the projections described herein are to nuclei implicated in the processing of noxious information. This implies a unique role for the CPA in somatoautonomic regulation.

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Section: Caudal and Rostral Ventrolateral Medullamentioning

confidence: 99%

Defining projections from the caudal pressor area of the caudal ventrolateral medulla

Sun

Panneton

2004

J. Comp. Neurol.

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“…Injection of kynurenic acid into the RVLM reduced the pressor and sympathoexcitatory effects evoked by hypothalamic stimulation, 24 whereas selective blockade of NMDA receptors by AP7 microinjection attenuated the hypertension induced by bilateral common carotid artery occlusion. 25 Ionotropic EAA receptors in the CVLM mediate glutamatergic input impinging on CVLM neurons that inhibit rostral pressor neurons. 11 When the mixture of AP7 and DNQX was microinjected in the CVLM, we observed significant increases in baseline blood pressure and SNA.…”

Section: Discussionmentioning

confidence: 99%

Metabotropic glutamate receptors in the ventrolateral medulla of rats.

Tsuchihashi

Averill

1993

Hypertension

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We investigated the hypothesis that stimulation of metabotropic excitatory amino acid receptors in the ventrolateral medulla evokes cardiovascular responses. Thus, (15,3/?)-l-aminocyclopentane-l,3-dicarboxylic acid [(1S,3/J)-ACPD], a selective agonist of metabotropic excitatory amino acid receptors, was microinjected into the rostral or caudal ventrolateral medulla of halothane-anesthetized Sprague-Dawley rats. Microinjections of (lS,3/f)-ACPD (100 pmol-1 nmol) into the rostral ventrolateral medulla produced dose-dependent increases in mean arterial pressure (+20±4 mm Hg by 100 praol and +35±2 mm Hg by 1 nmol, p< 0.01 versus artificial cerebrospinal fluid) and integrated splanchnic sympathetic nerve activity (+17±3% and +46±4%, respectively, p<0.01), whereas (15,3/f)-ACPD microinjected into the caudal ventrolateral medulla decreased mean arterial pressure (-28±2 mm Hg by 100 pmol and -48±6 mm Hg by 1 nmol, p<0.01 versus artificial cerebrospinal fluid) and splanchnic sympathetic nerve activity (-24±4% and -49±5%, p<0.01). The blockade of ionotropic excitatory amino acid receptors by the combined injection of 2-amino-7-phosphonoheptanoic acid (200 pmol) and 6,7-dinitroquinoxaline-2,3-dione ( t is well appreciated that L-glutamate (Glu) is a primary excitatory neurotransmitter in the central nervous system. Glu or other excitatory amino acids (EAA) may act at receptors that are ligand-gated ion channels and are referred to as ionotropic EAA receptors.1 These receptors exhibit selective responsiveness to 7V-methyl-D-aspartic acid (NMDA), kainic acid, or a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA);

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“…In the RVLM, the NMDAR mediates the pressor response induced by carotid body chemoreceptor (Kubo et al, 1993), local NMDA application, and carotid clamping (Lin et al, 1995). These responses are mediated by the NMDAR because they are attenuated by NMDA antagonists (Kao et al, 1991;Lin et al, 1995Lin et al, , 1997.…”

mentioning

confidence: 99%

The Hypotensive Action of Rilmenidine is Dependent on FunctionalN-Methyl-d-aspartate Receptor in the Rostral Ventrolateral Medulla of Conscious Spontaneously Hypertensive Rats

Zhang¹,

Abdel‐Rahman²

2002

J Pharmacol Exp Ther

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Rilmenidine is a second-generation centrally acting antihypertensive drug that acts mainly through the activation of the imidazoline (I 1 ) receptor in the rostral ventrolateral medulla (RVLM). To investigate the contribution of the N-methyl-D-aspartate receptor (NMDAR) to the hypotensive action of rilmenidine, experiments were undertaken in conscious male spontaneously hypertensive rats (SHRs). Microinjection of cumulative doses of rilmenidine (10, 20, and 40 nmol) at 10-to 15-min intervals, into the RVLM elicited dose-dependent hypotensive and bradycardic response. Pretreatment with intra-RVLM 2-amino-5-phosphonopentanoic acid (AP5) (2 nmol), a selective NMDAR antagonist, not only abolished the hypotensive response elicited by intra-RVLM rilmenidine (40 nmol) but also converted it to a pressor response (Ϫ24 Ϯ 1 versus 17 Ϯ 7 mm Hg; P Ͻ 0.05) and significantly attenuated the bradycardic response (Ϫ72 Ϯ 18 versus Ϫ24 Ϯ 20 bpm; P Ͻ 0.05). The blood pressure response to intra-RVLM N-methyl-D-aspartate (NMDA) depended on the dose applied. Whereas intra-RVLM NMDA (Ͼ20 pmol) produced the expected pressor response, a lower dose (10 pmol) reduced mean arterial pressure (MAP) (Ϫ14 Ϯ 3 mm Hg) and heart rate (Ϫ21 Ϯ 12 bpm). The divergent MAP responses were attenuated by intra-RVLM AP5 (2 nmol), which implicates the NMDAR in the pressor as well as the depressor response. The present findings suggest that the NMDAR in the RVLM of the SHR 1) exerts dual effects on blood pressure, with the response type depending on the level of NMDAR activation, and 2) plays a pivotal role in the hypotension mediated by I 1 receptor activation in the RVLM.

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NMDA antagonists attenuate hypertension induced by carotid clamping in the rostral ventrolateral medulla of rats

Cited by 23 publications

References 22 publications

Defining projections from the caudal pressor area of the caudal ventrolateral medulla

Defining projections from the caudal pressor area of the caudal ventrolateral medulla

Metabotropic glutamate receptors in the ventrolateral medulla of rats.

The Hypotensive Action of Rilmenidine is Dependent on FunctionalN-Methyl-d-aspartate Receptor in the Rostral Ventrolateral Medulla of Conscious Spontaneously Hypertensive Rats

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