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

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