Blood oxygen transport in stressed striped bass (Morone saxatilis): role of beta-adrenergic responses |
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Authors: | Mikko Nikinmaa Joseph J. Cech Jr. Maryann McEnroe |
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Affiliation: | (1) Department of Chemistry, Stanford University, 94305 Stanford, California, USA;(2) Department of Wildlife and Fisheries Biology, University of California, 95616 Davis, California, USA;(3) Present address: Division of Physiology, Department of Zoology, University of Helsinki, Arkadiankatu 7, SF-00100 Helsinki 10 |
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Abstract: | Summary Strenuous 5-min exercise resulted in a 0.3 unit drop in the dorsal aortic pH of striped bass. The acidosis was metabolic: the blood lactate concentration increased during the exercise, whereas blood CO2 tension decreased. Dorsal aortic oxygen content was maintained despite the acidosis. This was a result of increased blood O2 tension, haemoglobin concentration and red cell volume, decreased cellular nucleoside triphosphate (NTP) concentration, and decreased proton gradient across the red cell membrane. When the fish were treated with the beta-antagonist, propranolol, before the exercise, the arterial oxygen content decreased significantly in the stress. The mean cellular haemoglobin concentration and cellular NTP concentration increased slightly, and the proton gradient across the red cell membrane decreased less than in control exercise. These results show that the beta-adrenergic responses of striped bass red cells play an important role in maintaining the arterial O2 content in stress.Abbreviation NTP nucleoside triphosphates |
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