Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat

Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat

Author Tolentino-Silva, Fatima Rosaria Paulino Autor UNIFESP Google Scholar
Russo, A.k. Autor UNIFESP Google Scholar
Cravo, Sergio Luiz Autor UNIFESP Google Scholar
Lopes, Oswaldo Ubriaco Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract 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.
Keywords ventral surface of the medulla
breathing pattern
cardiorespiratory control
kynurenic acid
Language English
Date 1998-10-01
Published in Brazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 31, n. 10, p. 1339-1343, 1998.
ISSN 0100-879X (Sherpa/Romeo, impact factor)
Publisher Associação Brasileira de Divulgação Científica
Extent 1339-1343
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000076614900016
SciELO ID S0100-879X1998001000016 (statistics in SciELO)

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