Neurotransmitter profiles in fish gills: Putative gill oxygen chemoreceptors

Control of cardiorespiratory function in response to hypoxia in an air-breathing fish, the African sharptooth catfish, Clarias gariepinus

“…However, the distribution and orientation of these O 2 chemoreceptors among the different gill arches is not uniform among species (Milsom, 2012). Again, the distribution and orientation of the receptors involved in the modulation of f H seem to be species-specific.…”

“…In most fish species studied so far the cardiac response to hypoxia is a pronounced bradycardia (Gilmour and Perry, 2007;Perry et al, 2009aPerry et al, , 2009bMilsom, 2012) and the receptors promoting these responses have been invariably confined to the gills. However, the distribution and orientation of these O 2 chemoreceptors among the different gill arches is not uniform among species (Milsom, 2012).…”

“…In most unimodal water-breathing species studied so far, the O 2 chemoreceptors eliciting hypoxic bradycardia appear to sense only the inspired water (Milsom, 2012). In Amia calva the reflex bradycardia is mediated by externally oriented receptors (McKenzie et al, 1991a(McKenzie et al, , 1991b and internally oriented receptors (monitoring the PO 2 of arterial blood).…”

Characterisation of putative oxygen chemoreceptors in bowfin (Amia calva)

“…Although the exact mechanism behind this hypertrophy is unknown it is probably related to the increased turnover and synthesis of neurotransmitters associated with the increased activity of the chemoreceptors. In the gills of all fish species studied to date (for review, see Porteus et al, 2012), serotonin-containing neuroepithelial cells (NECs), which are putative peripheral arterial O 2 chemoreceptors, have been found, and evidence suggests that the NECs found in zebrafish (Danio rerio) and mangrove rivulus (Kryptolebias marmoratus) gills also increase in size during exposure to sustained hypoxia (Jonz et al, 2004;Regan et al, 2011).…”

The sensing of respiratory gases in fish: Mechanisms and signalling pathways

“…For a thorough account of the cardiorespiratory reflexes associated with hypoxia and hypercapnia, the reader is referred to the paper (this volume) by Burleson (2015) and other detailed review articles (Bushnell and Jones, 1992;Butler and Metcalfe, 1988;Farrell, 1993;Farrell and Jones, 1992;Fritsche and Nilsson, 1992;Gilmour and Perry, 2007;Olson, 1998;Perry et al, 2009a;Gilmour, 1999, 2010;Randall, 1982;Taylor, 1992). In addition, a number of previous reviews have covered aspects of chemoreception in fish (Burleson, 2009;Burleson et al, 1992;Gilmour, 2001;Gilmour and Perry, 2007;Jones and Milsom, 1982;Jonz and Nurse, 2006;Milsom, 1995Milsom, , 2012Milsom et al, 1999;Perry et al, 2009b;Porteus et al, 2012;Shelton et al, 1986).…”