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Ionotropic but not metabotropic glutamatergic receptors in the Locus Coeruleus modulate the hypercapnic ventilatory response in unanesthetized rats
Author(s) -
Dias Mirela Barros,
Taxini Camila L,
Puga Cintia C.I.,
Gargaglioni Luciane H,
Bícego Kênia C.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1137.23
Subject(s) - ionotropic effect , hypercapnia , chemoreceptor , metabotropic glutamate receptor , chemistry , endocrinology , medicine , glutamate receptor , anesthesia , pharmacology , receptor , respiratory system
Central chemoreception is an important mechanism by which changes in tissue CO 2 /H + regulate breathing, and the Locus coeruleus (LC) is one of many putative central chemoreceptor sites. Here, we studied the contribution of LC glutamatergic receptors on ventilatory, cardiovascular and thermal responses to hypercapnia. To this end, we measured pulmonary ventilation (VE), body temperatures (Tb), mean arterial pressure (MAP) and heart rate (fH) of male Wistar rats before and after microinjection of Kynurenic Acid (KY, an ionotropic glutamate receptors antagonist, 10 mM) or α‐methyl‐4‐carboxyphenylglycine (MCPG, a metabotropic glutamate receptor antagonist, 10 ηM) unilateraly into the LC, followed by 60 minutes of air or hypercapnia exposure (7% CO 2 ). Ventilatory response to hypercapnia was higher in animals treated with KY intra‐LC (1899 ± 83 mL kg −1 min −1 ) compared to the control group (1141 ± 64 mL kg −1 min −1 ; P < 0.01). However, the MCPG treatment within the LC had no effect on the hypercapnia‐induced hyperpnea. The cardiovascular and thermal control were not affected by hypercapnia or by the injection of KY and MCPG in the LC. These data suggest that the glutamate acting on ionotropic but not metabotropic receptors in the LC exerts an inibitory modulation of hypercapnia‐induced hyperpnea. Financial support: FAPESP, CNPq, PROPe.