Free fatty acid metabolism in the air-breathing African catfish (Clarias gariepinus) during asphyxia.
In several waterbreathing fish species, hypoxia induces a decrease in plasma free fatty acid (FFA) levels as opposed to an increase in air-breathing mammals. We hypothesised that this change is coupled to the mode of breathing. Therefore, we followed the metabolic response of cannulated air-breathing African catfish to an 8-h asphyxia period. The hematocrit and hemoglobin increased significantly upon asphyxia. However, no change was observed in the mean cellular hemoglobin concentration, indicating that more erythrocytes were brought into circulation. A continuous increase in plasma lactate concentration during asphyxia showed permanent activation of anaerobic glycolysis, pointing to a persistent oxygen shortage. Plasma glucose levels did not change, but FFA levels decreased significantly upon asphyxia with a concomitant increase in plasma noradrenaline levels. Thus, these results suggest that in the air-breathing African catfish noradrenaline mediated a decrease in plasma FFA levels similar to that in waterbreathing fish species.
Van Heeswijk
J C F
JC
Department of Integrative Zoology, Institute of Biology Leiden, Leiden University, P.O. Box 9516, 2300 RA, Leiden, The Netherlands. heeswijk@rulsfb.leidenuniv.nl
Van Pelt
J
J
Van den Thillart
G E E J M
GE
D000349:Africa; D000818:Animals; D001237:Asphyxia / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D002397:Catfishes / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood; D009638:Norepinephrine / Q000097:blood; D012119:Respiration
D005230:Fatty Acids, Nonesterified; D006454:Hemoglobins; D019344:Lactic Acid; D009638:Norepinephrine