Regulation of cardiac output and gut blood flow in the sea raven,Hemitripterus americanus |
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Authors: | Michael Axelsson William R. Driedzic Anthony P. Farrell Stefan Nilsson |
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Affiliation: | (1) Huntsman Marine Science Centre, E0G 2XO St. Andrews, NB, Canada;(2) Biology Department, Mount Allison University, E0A 3CO Sackville, NB, Canada;(3) Present address: Comparative Neuroscience Unit, Department of Zoophysiology, University of Göteborg, P.O. Box 250 59, S-400 31 Göteborg, Sweden;(4) Present address: Department of Biological Sciences, Simon Fraser University, V5A 1S6 Burnaby, BC, Canada |
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Abstract: | Coeliac artery blood flow (Fca) before and after feeding was recorded in the sea raven. To obtain basic information about the scope of cardiovascular adjustment in the sea raven, a separate series of experiments was performed, in which ventral (Pva), and dorsal (Pda) aortic blood pressure, heart rate (HR) and cardiac output (jaz) were monitored during rest and encouraged exercise.Measurements of coeliac artery flow showed that visceral blood flow is substantial, particularly after feeding, and variations in the visceral vascular conductance affect Pda directly. Simultaneous recordings of intestinal and dorsal aortic blood pressures showed no measurable difference in the two arterial pressures, refuting the idea of a vascular control at the level of the main coeliac artery. Thus, in the sea raven, the adrenergic tonus affecting the visceral vasculature presumably acts at the arteriolar level.Sea ravens encouraged to exercise increased theirjaz by 64%; 32% through HR and 25% through stroke volume. The increase injaz during encouraged exercise was sufficient to produce an elevation of both Pva and Pda, despite an increase of systemic vascular conductance, -adrenoceptor blockade with sotalol, however, severely impaired the increase injaz during exercise, and the change in Pda was reversed.During rest there were both an adrenergic and a cholinergic tonus affecting the HR, as revealed by the effects of injected pharmacological antagonists. Swimming activity decreased the cholinergic tonus, while the adrenergic tonus increased. |
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Keywords: | Hemitripterus americanus teleost fish circulatory system gastrointestinal blood flow |
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