Hypercarbic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): the role of branchial CO2 chemoreceptors

Autor(es)

Boijink, Cheila de Lima ^[1] ; Florindo, Luiz Henrique ^{[2, 3]} ; Costa Leite, Cleo A. ^{[1, 3]} ; Kalinin, Ana Lucia ^{[1, 3]} ; Milsom, William K. ^[4] ; Rantin, Francisco Tadeu ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, Dept Physiol Sci, BR-13565905 Sao Carlos, SP - Brazil

^[2] Sao Paulo State Univ, UNESP, Dept Bot & Zool, Aquaculture Ctr, CAUNESP, BR-15054000 Sao Jose Do Rio Preto, SP - Brazil

^[3] Natl Inst Sci & Technol Comparat Physiol, FAPESP CNPq, Campinas, SP - Brazil

^[4] Univ British Columbia, Dept Zool, Vancouver, BC V6T 1Z4 - Canada

• Tipo de documento: Artigo Científico
• Fonte: Journal of Experimental Biology; v. 213, n. 16, p. 2797-2807, AUG 15 2010.
• Citações Web of Science: 8

Resumo

The aim of the present study was to determine the roles that externally versus internally oriented CO(2)/H(+)-sensitive chemoreceptors might play in promoting cardiorespiratory responses to environmental hypercarbia in the air-breathing fish, Hoplerythrinus unitaeniatus (jeju). Fish were exposed to graded hypercarbia (1, 2.5, 5, 10 and 20% CO(2)) and also to graded levels of environmental acidosis (pH similar to 7.0, 6.0, 5.8, 5.6, 5.3 and 4.7) equal to the pH levels of the hypercarbic water to distinguish the relative roles of CO(2) versus H(+). We also injected boluses of CO(2)-equilibrated solutions (5, 10 and 20% CO(2)) and acid solutions equilibrated to the same pH as the CO(2) boluses into the caudal vein (internal) and buccal cavity (external) to distinguish between internal and external stimuli. The putative location of the chemoreceptors was determined by bilateral denervation of branches of cranial nerves IX (glossopharyngeal) and X (vagus) to the gills. The data indicate that the chemoreceptors eliciting bradycardia, hypertension and gill ventilatory responses (increased frequency and amplitude) to hypercarbia are exclusively branchial, externally oriented and respond specifically to changes in CO(2) and not H(+). Those involved in producing the cardiovascular responses appeared to be distributed across all gill arches while those involved in the gill ventilatory responses were located primarily on the first gill arch. Higher levels of aquatic CO(2) depressed gill ventilation and stimulated air breathing. The chemoreceptors involved in producing air breathing in response to hypercarbia also appeared to be branchial, distributed across all gill arches and responded specifically to changes in aquatic CO(2). This would suggest that chemoreceptor groups with different orientations (blood versus water) are involved in eliciting air-breathing responses to hypercarbia in jeju. (AU)

• Processo FAPESP: 98/13534-1 - William Kenneth Milsom | University of British Columbia - Canadá
• Beneficiário: Francisco Tadeu Rantin
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 00/12382-5 - Regulação dos reflexos cardio-respiratórios em peixes tropicais
• Beneficiário: Francisco Tadeu Rantin
• Modalidade de apoio: Auxílio à Pesquisa - Regular