1. Enhanced oxygen unloading in two marine percomorph teleosts.
- Author
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Shu JJ, Heuer RM, Hannan KD, Stieglitz JD, Benetti DD, Rummer JL, Grosell M, and Brauner CJ
- Subjects
- Animals, Erythrocytes metabolism, Fish Proteins metabolism, Fishes blood, Hemoglobins metabolism, Kinetics, Oxygen blood, Perciformes blood, Salmonidae blood, Salmonidae physiology, Species Specificity, Fishes physiology, Oxygen physiology, Perciformes physiology
- Abstract
Teleost fishes are diverse and successful, comprising almost half of all extant vertebrate species. It has been suggested that their success as a group is related, in part, to their unique O
2 transport system, which includes pH-sensitive hemoglobin, a red blood cell β-adrenergic Na+ /H+ exchanger (RBC β-NHE) that protects red blood cell pH, and plasma accessible carbonic anhydrase which is absent at the gills but present in some tissues, that short-circuits the β-NHE to enhance O2 unloading during periods of stress. However, direct support for this has only been examined in a few species of salmonids. Here, we expand the knowledge of this system to two warm-water, highly active marine percomorph fish, cobia (Rachycentron canadum) and mahi-mahi (Coryphaena hippurus). We show evidence for RBC β-NHE activity in both species, and characterize the Hb-O2 transport system in one of those species, cobia. We found significant RBC swelling following β-adrenergic stimulation in both species, providing evidence for the presence of a rapid, active RBC β-NHE in both cobia and mahi-mahi, with a time-course similar to that of salmonids. We generated oxygen equilibrium curves (OECs) for cobia blood and determined the P50 , Hill, and Bohr coefficients, and used these data to model the potential for enhanced O2 unloading. We determined that there was potential for up to a 61% increase in O2 unloading associated with RBC β-NHE short-circuiting, assuming a - 0.2 ∆pHa-v in the blood. Thus, despite phylogenetic and life history differences between cobia and the salmonids, we found few differences between their Hb-O2 transport systems, suggesting conservation of this physiological trait across diverse teleost taxa., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2022
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