title: Purinergic transmission in the rostral but not caudal medullary raphe contributes to the hypercapnia-induced ventilatory response in unanesthetized rats.
abstract: The medullary raphe (MR) is a putative central chemoreceptor site, contributing to hypercapnic respiratory responses elicited by changes in brain PCO2/pH. Purinergic mechanisms in the central nervous system appear to contribute to central chemosensitivity. To further explore the role of P2 receptors within the rostral and caudal MR in relation to respiratory control in room air and hypercapnic conditions, we performed microinjections of PPADS, a non-selective P2X antagonist, in conscious rats. Microinjections of PPADS into the rostral or caudal MR produced no changes in the respiratory frequency, tidal volume and ventilation in room air condition. The ventilatory response to hypercapnia was attenuated after microinjection of PPADS into the rostral but not in the caudal MR when compared to the control group (vehicle microinjection). These data suggest that P2X receptors in the rostral MR contribute to the ventilatory response to CO2, but do not participate in the tonic maintenance of ventilation under room air condition in conscious rats.
authors: Department of Physiology, University of São Paulo-USP/FMRP, Ribeirão Preto, SP, Brazil. glauber@ymail.com
authors: Glauber S F
authors: GS
authors: da Silva
authors: Davi J A
authors: DJ
authors: Moraes
authors: Humberto
authors: H
authors: Giusti
authors: Mirela Barros
authors: MB
authors: Dias
authors: Mogens L
authors: ML
authors: Glass
mesh_terms: D000818:Animals; D003243:Consciousness; D006935:Hypercapnia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008845:Microinjections; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D012123:Pulmonary Ventilation / Q000502:physiology*; D011687:Purines / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000031:analogs & derivatives; D011903:Raphe Nuclei / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D058469:Receptors, Purinergic P2X / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D010975:Platelet Aggregation Inhibitors; D011687:Purines; D058469:Receptors, Purinergic P2X; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate