Control of vascular tone in notothenioid fishes is determined by phylogeny, not environmental temperature

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2001-04, Vol.280 (4), p.1197-R1205
• Main Authors: Egginton, S, Forster, M. E, Davison, W
• Format: Article
• Language: English
• Subjects: Animals; Antarctic Regions; Aorta - drug effects; Aorta - physiology; Arteries - drug effects; Arteries - physiology; Atropine - pharmacology; Blood Pressure - drug effects; Body Temperature; Branchial Region - blood supply; Carbachol - pharmacology; Ecosystem; Environment; Epinephrine - pharmacology; Heart Rate - drug effects; In Vitro Techniques; Muscle Contraction - drug effects; Muscle Tonus; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - physiology; New Zealand; Norepinephrine - pharmacology; Perciformes - classification; Perciformes - genetics; Perciformes - physiology; Phylogeny; Potassium Chloride - pharmacology; Serotonin - pharmacology; Sotalol - pharmacology; Species Specificity
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.2001.280.4.R1197

Department of Zoology, University of Canterbury, Private Bag 4800, Christchurch, New Zealand We examined potential vasomotor control mechanisms in an Antarctic fish ( Trematomus bernacchii ; usual core temperature approximately 1°C), comparing sensitivity to agonists by means of the cumulative dose response and potency with reference to depolarization by 50 mM KCl. In efferent branchial arteries, norepinephrine (NE) produced ~20% of the maximal KCl tension and ~40% in the presence of 10 3 M sotalol, suggesting a modest contribution of - and -adrenergic tonus [half-maximal response (pEC 50 ) = 6.29 ± 0.37 M]. Carbachol (CBC) and serotonin (5-HT) had different sensitivities (pEC 50   = 4.50 ± 0.40 and 6.82 ± 0.08 M, respectively) but similar potencies (21.6 ± 11.1 and 31.1 ± 5.3% of KCl). A related species from warmer waters around New Zealand, Paranotothenia angustata, had similar vascular reactivity for NE (pEC 50  = 5.48 ± 0.31 M), CBC (pEC 50   = 4.94 ± 0.22 M), and methysergide-sensitive vasoconstriction with 5-HT (pEC 50  = 6.22 ± 0.40 M). Agonist potencies were 9, 65,   and 45% that of KCl, respectively. Bovichtus variegatus , a member of the phylogenetic sister group to the notothenioids, also gave broadly similar responses. In contrast, Dissostichus mawsoni , a pelagic Antarctic notothenioid, showed a dominance of vasodilatation over vasoconstriction, with sensitive isoprenaline (pEC 50  = 6.66   ± 0.05 M) but weak serotonergic (5.2 ± 1.5% KCl) responses. The unusual dominance of serotonergic control appears to be primarily a consequence of evolutionary lineage rather than low environmental temperature, but the pattern may be modified according to functional demand. Antarctica; catecholamines; myography; serotonin