Carbohydrate management, anaerobic metabolism, and adenosine levels in the armoured catfish, Liposarcus pardalis (castelnau), during hypoxia.
The armoured catfish, Liposarcus pardalis, tolerates severe hypoxia at high temperatures. Although this species can breathe air, it also has a strong anaerobic metabolism. We assessed tissue to plasma glucose ratios and glycogen and lactate in a number of tissues under "natural" pond hypoxia, and severe aquarium hypoxia without aerial respiration. Armour lactate content and adenosine in brain and heart were also investigated. During normoxia, tissue to plasma glucose ratios in gill, brain, and heart were close to one. Hypoxia increased plasma glucose and decreased tissue to plasma ratios to less than one, suggesting glucose phosphorylation is activated more than uptake. High normoxic white muscle glucose relative to plasma suggests gluconeogenesis or active glucose uptake. Excess muscle glucose may serve as a metabolic reserve since hypoxia decreased muscle to plasma glucose ratios. Mild pond hypoxia changed glucose management in the absence of lactate accumulation. Lactate was elevated in all tissues except armour following aquarium hypoxia; however, confinement in aquaria increased armour lactate, even under normoxia. A stress-associated acidosis may contribute to armour lactate sequestration. High plasma lactate levels were associated with brain adenosine accumulation. An increase in heart adenosine was triggered by confinement in aquaria, although not by hypoxia alone.
Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1C 5S7. tmacc@mun.ca
Tyson James
TJ
Maccormack
Johanne Mari
JM
Lewis
Vera Maria Fonseca
VM
Almeida-Val
Adalberto Luis
AL
Val
William Robert
WR
Driedzic
D000138:Acidosis / Q000378:metabolism; D000241:Adenosine / Q000378:metabolism*; D000693:Anaerobiosis; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000097:blood; D050260:Carbohydrate Metabolism; D002397:Catfishes / Q000378:metabolism*; D004734:Energy Metabolism; D005880:Gills / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006854:Hydrocortisone / Q000097:blood; D000860:Hypoxia; D007773:Lactates / Q000097:blood / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism; D009132:Muscles / Q000737:chemistry; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000502:physiology*; D010766:Phosphorylation; D012119:Respiration; D013696:Temperature
D001786:Blood Glucose; D007773:Lactates; D008112:Liver Glycogen; D005947:Glucose; D000241:Adenosine; D010100:Oxygen; D002118:Calcium; D006854:Hydrocortisone