Effects of afferent input on the breathing pattern continuum in the tambaqui (Colossoma macropomum).
This study used a decerebrate and artificially-ventilated preparation to examine the roles of various afferent inputs in breathing pattern formation in the tambaqui (Colossoma macropomum). Three general breathing patterns were observed: (1) regular breathing; (2) frequency cycling and (3) episodic breathing. Under normoxic, normocapnic conditions, 50% of control fish exhibited regular continuous breathing and 50% exhibited frequency cycling. Denervation of the gills and oro-branchial cavity promoted frequency cycling. Central denervation of the glossopharyngeal and vagus nerves produced episodic breathing. Regardless of the denervation state, hyperoxia produced either frequency cycling or episodic breathing while hypoxia and hypercarbia shifted the pattern to frequency cycling and continuous breathing. We suggest that these breathing patterns represent a continuum from continuous to episodic breathing with waxing and waning occupying an intermediate stage. The data further suggest that breathing pattern is influenced by both specific afferent input from chemoreceptors and generalised afferent input while chemoreceptors specific for producing changes in breathing pattern may exist in fish.
Reid
Stephen G
SG
Department of Life Sciences, University of Toronto at Scarborough, 1265 Military Trail, Toronto, Ont., Canada M1C 1A4. sgreid@utsc.utoronto.ca
Sundin
Lena
L
Florindo
Luis Henrique
LH
Rantin
Francisco Tadeu
FT
Milsom
William K
WK
D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology; D003655:Decerebrate State / Q000503:physiopathology*; D003714:Denervation / Q000379:methods; D005399:Fishes; D006353:Heart-Assist Devices; D006935:Hypercapnia / Q000503:physiopathology; D018496:Hyperoxia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D010100:Oxygen / Q000494:pharmacology; D010525:Peripheral Nerves / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology; D012119:Respiration; D012143:Respiratory Physiological Phenomena
D002245:Carbon Dioxide; D010100:Oxygen