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Putative pathways involved in cardiovascular responses evoked from the caudal pressor area
Braz. j. med. biol. res ; 27(10): 2467-79, Oct. 1994. graf
Article Dans Anglais | LILACS | ID: lil-152630
ABSTRACT
1. The caudal pressor area (CPA) is a recently identified site within the ventrolateral medulla which is involved in cardiovascular regulation. CPA chemical stimulation by L-glutamate produces an increase in arterial blood pressure (ABP) while its inhibition by GABA or glycine evokes marked hypotension. In the present study, we sought to determine the potential neural pathways underlyng these responses. 2. In urethane-anesthetized, paralyzed, artificially ventilated rats, CPA inhibition by bilateral microinjection of the inhibitory amino acid glycine (Gly, 100 nmol 200 nl-1 site-1) produced an average decrease of -38 + or - 4.3 mmHg in ABP (n = 6). Ten min after bilateral microinjection of the broad-spectrum glutamate antagonist kynurenic acid (KYN, 2 nmol 200 nl-1 site-1) into the cauldal ventrolateral medulla (CVLM) depressor responses to CPA inhibition were virtually abolished (-3 + or - 1.7 mmHg, P<0.05). Similar microinjection of KYN into the rostral ventrolateral medulla (RVLM) or into the CPA itself did not modify depressor responses to CPA inhibiton by glycine. 3. CPA stimulation by bilateral microinjection of the excitatory amino acid L-glutamate (L-glu, 50 nmol 200 nl-1 site-1) produced an increase in ABP (+43 + or - 5.4 mmHg, N= 6). Bilateral microinjection of the GABA A antagonist bicuculline methiodide (BIC, 200 pmol 200 nl-1 site-1) into the CVLM markedly reduced pressor responses to CPA stimulation (+6 + or - 2.7 mmHg, P<0.05). Similar application of BIC into the RVLM or CPA did not modify pressor responses to CPA stimulation by glutamic acid
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Indice: LILAS (Amériques) Sujet Principal: Moelle osseuse / Pression artérielle / Glutamates / Acide kynurénique / Voies nerveuses Limites du sujet: Animaux langue: Anglais Texte intégral: Braz. j. med. biol. res Thème du journal: Biologie / Médicament Année: 1994 Type: Article

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Indice: LILAS (Amériques) Sujet Principal: Moelle osseuse / Pression artérielle / Glutamates / Acide kynurénique / Voies nerveuses Limites du sujet: Animaux langue: Anglais Texte intégral: Braz. j. med. biol. res Thème du journal: Biologie / Médicament Année: 1994 Type: Article