Heme oxygenase-1 (HO-1) mediated respiratory responses to hypoxia in the goldfish, Carassius auratus.
In this study we investigated the role of heme oxygenase-1 (HO-1) in modulating the hypoxic and hyperoxic ventilatory responses of goldfish (Carassius auratus) acclimated to 7 and 25°C. HO-1 was present in the neuroepithelial cells (NECs; putative branchial O2 chemoreceptors) of fish acclimated to 7°C only. Hypoxia exposure increased gill HO-1 activity in 7°C fish (14.0±1.4 to 42.5±3.2pmolbilirubinmin(-1)mgprotein(-1)). Inhibition of HO-1 activity with zinc protophorphyrin IX (ZnPPIX) increased the ventilation frequency response to acute hypoxia (30mmHg); frequency increased from 48.3±5.1 to 137.4±16.0 breaths per min (BPM) in hypoxic 7°C fish treated with ZnPPIX compared to 46.2±4.2 to 77.9±5.3 BPM in control fish. Unlike in the control (untreated) 7°C fish exposed to hyperoxia, fish injected with ZnPPIX did not significantly decrease breathing frequency. Inhibiting HO-1 activity was without effect on the hypoxic or hyperoxic ventilatory responses of fish acclimated to 25°C. Based on these observations, we suggest that HO-1 plays an inhibitory role in regulating breathing frequency but only in goldfish acclimated to 7°C.
Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada. Electronic address: vtzan032@uottawa.ca.
Velislava
V
Tzaneva
Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada. Electronic address: sfperry@uottawa.ca.
Steve F
SF
Perry
D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D015153:Blotting, Western; D004791:Enzyme Inhibitors / Q000494:pharmacology; D029941:Fish Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005880:Gills / Q000187:drug effects / Q000201:enzymology / Q000294:innervation / Q000502:physiology*; D006054:Goldfish / Q000502:physiology*; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018496:Hyperoxia; D000860:Hypoxia; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D046569:Neuroepithelial Cells / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000032:analysis*; D011524:Protoporphyrins / Q000494:pharmacology; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D013696:Temperature
D004791:Enzyme Inhibitors; D029941:Fish Proteins; D011524:Protoporphyrins; C017803:zinc protoporphyrin; D051547:Heme Oxygenase-1; D010100:Oxygen
Breathing; Gill; Neuroepithelial cell (NEC); Oxygen; Serotonin; Ventilation