Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat
Several studies demonstrate that, within the ventral medullary surface (VMS), excitatory amino acids are necessary components of the neural circuits involved in the tonic and reflex control of respiration and circulation. In the present study we investigated the cardiorespiratory effects of unilater...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Associação Brasileira de Divulgação Científica
1998-10-01
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| Series: | Brazilian Journal of Medical and Biological Research |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998001000016 |
| _version_ | 1818892982905995264 |
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| author | F.P. Tolentino-Silva A.K. Russo S.L. Cravo O.U. Lopes |
| author_facet | F.P. Tolentino-Silva A.K. Russo S.L. Cravo O.U. Lopes |
| author_sort | F.P. Tolentino-Silva |
| collection | DOAJ |
| description | Several studies demonstrate that, within the ventral medullary surface (VMS), excitatory amino acids are necessary components of the neural circuits involved in the tonic and reflex control of respiration and circulation. In the present study we investigated the cardiorespiratory effects of unilateral microinjections of the broad spectrum glutamate antagonist kynurenic acid (2 nmol/200 nl) along the VMS of urethane-anesthetized rats. Within the VMS only one region was responsive to this drug. This area includes most of the intermediate respiratory area, partially overlapping the rostral ventrolateral medulla (IA/RVL). When microinjected into the IA/RVL, kynurenic acid produced a respiratory depression, without changes in mean arterial pressure or heart rate. The respiratory depression observed was characterized by a decrease in ventilation, tidal volume and mean inspiratory flow and an increase in respiratory frequency. Therefore, the observed respiratory depression was entirely due to a reduction in the inspiratory drive. Microinjections of vehicle (200 nl of saline) into this area produced no significant changes in breathing pattern, blood pressure or heart rate. Respiratory depression in response to the blockade of glutamatergic receptors inside the rostral VMS suggests that neurons at this site have an endogenous glutamatergic input controlling the respiratory cycle duration and the inspiratory drive transmission. |
| first_indexed | 2024-12-19T18:05:22Z |
| format | Article |
| id | doaj.art-1142c18e64164bef9011ad651e4cc6df |
| institution | Directory Open Access Journal |
| issn | 0100-879X 1414-431X |
| language | English |
| last_indexed | 2024-12-19T18:05:22Z |
| publishDate | 1998-10-01 |
| publisher | Associação Brasileira de Divulgação Científica |
| record_format | Article |
| series | Brazilian Journal of Medical and Biological Research |
| spelling | doaj.art-1142c18e64164bef9011ad651e4cc6df2022-12-21T20:11:28ZengAssociação Brasileira de Divulgação CientíficaBrazilian Journal of Medical and Biological Research0100-879X1414-431X1998-10-013110133910.1590/S0100-879X1998001000016Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the ratF.P. Tolentino-SilvaA.K. RussoS.L. CravoO.U. LopesSeveral studies demonstrate that, within the ventral medullary surface (VMS), excitatory amino acids are necessary components of the neural circuits involved in the tonic and reflex control of respiration and circulation. In the present study we investigated the cardiorespiratory effects of unilateral microinjections of the broad spectrum glutamate antagonist kynurenic acid (2 nmol/200 nl) along the VMS of urethane-anesthetized rats. Within the VMS only one region was responsive to this drug. This area includes most of the intermediate respiratory area, partially overlapping the rostral ventrolateral medulla (IA/RVL). When microinjected into the IA/RVL, kynurenic acid produced a respiratory depression, without changes in mean arterial pressure or heart rate. The respiratory depression observed was characterized by a decrease in ventilation, tidal volume and mean inspiratory flow and an increase in respiratory frequency. Therefore, the observed respiratory depression was entirely due to a reduction in the inspiratory drive. Microinjections of vehicle (200 nl of saline) into this area produced no significant changes in breathing pattern, blood pressure or heart rate. Respiratory depression in response to the blockade of glutamatergic receptors inside the rostral VMS suggests that neurons at this site have an endogenous glutamatergic input controlling the respiratory cycle duration and the inspiratory drive transmission.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998001000016ventral surface of the medullabreathing patterncardiorespiratory controlkynurenic acidrat |
| spellingShingle | F.P. Tolentino-Silva A.K. Russo S.L. Cravo O.U. Lopes Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat Brazilian Journal of Medical and Biological Research ventral surface of the medulla breathing pattern cardiorespiratory control kynurenic acid rat |
| title | Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat |
| title_full | Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat |
| title_fullStr | Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat |
| title_full_unstemmed | Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat |
| title_short | Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat |
| title_sort | respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat |
| topic | ventral surface of the medulla breathing pattern cardiorespiratory control kynurenic acid rat |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998001000016 |
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