Differential control of renal vs. adrenal sympathetic  nerve activity by NTS A<sub>2a</sub> and P<sub>2x</sub> purinoceptors

Scislo, Tadeusz J.; O’Leary, Donal S.

doi:10.1152/ajpheart.1998.275.6.h2130

Cited by 34 publications

(104 citation statements)

References 31 publications

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“…Studies from our laboratory addressing the role of NTS adenosine receptor subtypes in regional sympathetic control have shown that renal (RSNA) and postganglionic adrenal sympathetic nerve activity (post-ASNA, directed to the adrenal cortex and vasculature) are also uniformly activated and inhibited via stimulation of NTS A 1 and A 2a receptors, respectively (18,19,21). In contrast, the stimulation of both A 1 and A 2a adenosine receptor subtypes in the NTS increases preganglionic adrenal nerve activity (pre-ASNA), directed to the adrenal medulla (19,21). In addition, the stimulation of NTS A 1 adenosine receptors activates lumbar sympathetic nerve activity (LSNA), directed to the hindquarters, whereas stimulation of NTS A 2a receptors causes no significant changes in LSNA (18,21).…”

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confidence: 99%

Stimulation of NTS A₁ adenosine receptors evokes counteracting effects on hindlimb vasculature

McClure

O’Leary

Scislo

2005

American Journal of Physiology-Heart and Circulatory Physiology

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Our previous studies concluded that stimulation of the nucleus of the solitary tract (NTS) A2a receptors evokes preferential hindlimb vasodilation mainly via inducing increases in preganglionic sympathetic nerve activity (pre-ASNA) directed to the adrenal medulla. This increase in pre-ASNA causes the release of epinephrine and subsequent activation of ␤-adrenergic receptors that are preferentially located in the skeletal muscle vasculature. Selective activation of NTS A1 adenosine receptors evokes variable, mostly pressor effects and increases pre-ASNA, as well as lumbar sympathetic activity, which is directed to the hindlimb. These counteracting factors may have opposite effects on the hindlimb vasculature resulting in mixed vascular responses. Therefore, in chloralose-urethane-anesthetized rats, we evaluated the contribution of vasodilator versus vasoconstrictor effects of stimulation of NTS A 1 receptors on the hindlimb vasculature. We compared the changes in iliac vascular conductance evoked by microinjctions into the NTS of the selective A 1 receptor agonist N 6 -cyclopentyladenosine (330 pmol in 50 nl volume) in intact animals with the responses evoked after ␤-adrenergic blockade, bilateral adrenalectomy, bilateral lumbar sympathectomy, and combined adrenalectomy ϩ lumbar sympathectomy. In intact animals, stimulation of NTS A 1 receptors evoked variable effects: increases and decreases in mean arterial pressure and iliac conductance with prevailing pressor and vasoconstrictor effects. Peripheral ␤-adrenergic receptor blockade and bilateral adrenalectomy eliminated the depressor component of the responses, markedly potentiated iliac vasoconstriction, and tended to increase the pressor responses. Lumbar sympathectomy tended to decrease the pressor and vasoconstrictor responses. After bilateral adrenalectomy plus lumbar sympathectomy, a marked vasoconstriction in iliac vascular bed still persisted, suggesting that the vasoconstrictor component of the response to stimulation of NTS A 1 receptors is mediated mostly via circulating factors (e.g., vasopressin, angiotensin II, or circulating catecholamines released from other sympathetic terminals). These data strongly suggest that stimulation of NTS A 1 receptors exerts counteracting effects on the iliac vascular bed: activation of the adrenal medulla and ␤-adrenergic vasodilation versus vasoconstriction mediated by neural and humoral factors.nucleus of the solitary tract; purinergic receptors; ␤-adrenergic blockade; adrenalectomy; lumbar sympathectomy; iliac vascular conductance NUMEROUS STUDIES from our laboratory and by others have shown that adenosine modulates cardiovascular control at the level of the nucleus of the solitary tract (NTS) (3, 4, 11, 12, 17-22, 24, 25). The NTS contains the greatest density of adenosine uptake sites in the central nervous system (5). Therefore, the physiological role of adenosine operating as a neuromodulator in the NTS appears potentially important. A natural source of adenosine in the NTS and other cardiovascular centers is...

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confidence: 99%

Stimulation of NTS A₁ adenosine receptors evokes counteracting effects on hindlimb vasculature

McClure

O’Leary

Scislo

2005

American Journal of Physiology-Heart and Circulatory Physiology

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“…The activation of P2 receptors in the NTS following stimulation of the HDA in this study seems to intermediate both the withdrawal in sympathetic tone and the release of epinephrine. Although it was previously shown that activation of A2a receptors induces release of catecholamines by the adrenal medulla [45,54], we believe that P2 receptors also partly contribute to epinephrine release in response to activation of the HDA. The findings here differ from previous evidence of sympathoinhibition to the adrenal gland [21,45].…”

Section: Hindlimb Vasodilation In Alerting-defense Responses Is Mediamentioning

confidence: 65%

“…Although it was previously shown that activation of A2a receptors induces release of catecholamines by the adrenal medulla [45,54], we believe that P2 receptors also partly contribute to epinephrine release in response to activation of the HDA. The findings here differ from previous evidence of sympathoinhibition to the adrenal gland [21,45]. The discrepancy can be explained by the fact that adrenal sympathetic nerve activity regulates secretion of catecholamines related both to cardiovascular control and glucose metabolism [55].…”

Section: Hindlimb Vasodilation In Alerting-defense Responses Is Mediamentioning

confidence: 65%

“…By contrast, it is known that the increase in HVC following activation of P2 receptors in NTS neurons supposedly results from a reduction in sympathetic nerve activity [21,45]. This discrepancy can be explained partly by excitatory projections from the NTS to inhibitory interneurons in the RVLM.…”

Section: Hindlimb Vasodilation In Alerting-defense Responses Is Mediamentioning

confidence: 94%

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Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat

Korim

Ferreira-Neto

Pedrino

et al. 2012

Purinergic Signalling

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In the nucleus tractus solitarii (NTS) of rats, blockade of extracellular ATP breakdown to adenosine reduces arterial blood pressure (AP) increases that follow stimulation of the hypothalamic defense area (HDA). The effects of ATP on NTS P2 receptors, during stimulation of the HDA, are still unclear. The aim of this study was to determine whether activation of P2 receptors in the NTS mediates cardiovascular responses to HDA stimulation. Further investigation was taken to establish if changes in hindlimb vascular conductance (HVC) elicited by electrical stimulation of the HDA, or activation of P2 receptors in the NTS, are relayed in the rostral ventrolateral medulla (RVLM); and if those responses depend on glutamate release by ATP acting on presynaptic terminals. In anesthetized and paralyzed rats, electrical stimulation of the HDA increased AP and HVC. Blockade of P2 or glutamate receptors in the NTS, with bilateral microinjections of suramin (10 mM) or kynurenate (50 mM) reduced only the evoked increase in HVC by 75 % or more. Similar results were obtained with the blockade combining both antagonists. Blockade of P2 and glutamate receptors in the RVLM also reduced the increases in HVC to stimulation of the HDA by up to 75 %. Bilateral microinjections of kynurenate in the RVLM abolished changes in AP and HVC to injections of the P2 receptor agonist α,β-methylene ATP (20 mM) into the NTS. The findings suggest that HDA-NTS-RVLM pathways in control of HVC are mediated by activation of P2 and glutamate receptors in the brainstem in alerting-defense reactions.

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“…12,13 . A estimulação quí-mica do NTS provoca vasodilatação muscular que parece envolver a redução do tono vasoconstrictor simpático, a liberação de catecolaminas pela adrenal e a liberação de NO de acordo com o subtipo de receptor purinérgico estimulado 14,15 . O NTS apresenta projeções diretas para o RVL, cujo significado funcional permanece ainda em grande parte desconhecido.…”

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Os Núcleos Vasomotores Do Bulbo E a Regulação Cardiovascular: Novas Evidências E Novas Questões

Cravo

Rosa²,

Kalassa³

et al. 2006

Medicina (Ribeirão Preto)

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RESUMO: Há mais de 30 anos foi proposto um modelo para explicar como o sistema nervoso central promove a regulação do sistema cardiovascular, onde os núcleos vasomotores do bulbo seriam as principais estruturas envolvidas no controle do reflexo cardiovascular. Segundo este modelo, o núcleo do trato solitário (NTS) é o primeiro núcleo a integrar as informações cardiovasculares vindas dos baroceptores e também parece integrar vias descendentes provenientes de núcleos superiores como o hipotálamo, importantes para as reações de alerta e defesa. Do NTS saem projeções excitatórias para a região caudoventrolateral (CVL) do bulbo, a qual inibe a região rostroventrolateral (RVL). Esta última região constitui a principal fonte de eferências excitatórias para os neurônios simpáticos pré-ganglionares (SPN), sendo responsá-vel pelo tonus simpático para o coração e vasos. Projeções importantes do CVL para estruturas diencefálicas (núcleo preóptico mediano, núcleo paraventricular do hipotálamo e núcleo supraóptico) também estão envolvidas no controle da composição e/ou volume do compartimento extracelular. A área depressora gigantocelular (GiDA) constitui outro possível centro vasomotor envolvido nos ajustes de fluxo sangüíneo por meio de projeções diretas para o SPN. No entanto, o meio pelo qual a GiDA exerce seu efeito vasodepressor ainda é desconhecido.Nos últimos 10 anos, nosso laboratório tem se dedicado a deslindar as vias e mecanismos neurais associados à regulação do fluxo sangüíneo visceral e muscular. Resultados obtidos ao longo destes estudos resultaram em evidências que são incompatíveis com o modelo proposto.Descritores: Pressão Arterial. NTS. RVL. CVL. 89 1-INTRODUÇÃOA perfusão do leito vascular capilar constitui um elemento essencial da homeostasia. É através do fluxo sangüíneo que percorre este território e das trocas que aí se realizam, que o interstício pode ser renovado, mantendo-se nas condições ideais para a homeostasia celular. A perfusão do leito capilar depende de níveis adequados de pressão sangüínea arterial, uma vez que esta constitui a força motriz que Capítulo IX

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Differential control of renal vs. adrenal sympathetic nerve activity by NTS A_2a and P_2x purinoceptors

Cited by 34 publications

References 31 publications

Stimulation of NTS A₁ adenosine receptors evokes counteracting effects on hindlimb vasculature

Stimulation of NTS A₁ adenosine receptors evokes counteracting effects on hindlimb vasculature

Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat

Os Núcleos Vasomotores Do Bulbo E a Regulação Cardiovascular: Novas Evidências E Novas Questões

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Differential control of renal vs. adrenal sympathetic nerve activity by NTS A2a and P2x purinoceptors

Cited by 34 publications

References 31 publications

Stimulation of NTS A1 adenosine receptors evokes counteracting effects on hindlimb vasculature

Stimulation of NTS A1 adenosine receptors evokes counteracting effects on hindlimb vasculature

Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat

Os Núcleos Vasomotores Do Bulbo E a Regulação Cardiovascular: Novas Evidências E Novas Questões

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Differential control of renal vs. adrenal sympathetic nerve activity by NTS A_2a and P_2x purinoceptors

Stimulation of NTS A₁ adenosine receptors evokes counteracting effects on hindlimb vasculature

Stimulation of NTS A₁ adenosine receptors evokes counteracting effects on hindlimb vasculature