title: Cold-acclimation leads to differential regulation of the steelhead trout (Oncorhynchus mykiss) coronary microcirculation.
abstract: The regulation of vascular resistance in fishes has largely been studied using isolated large conductance vessels, yet changes in tissue perfusion/vascular resistance are primarily mediated by the dilation/constriction of small arterioles. Thus we adapted mammalian isolated microvessel techniques for use in fish and examined how several agents affected the tone/resistance of isolated coronary arterioles (<150 μm ID) from steelhead trout (Oncorhynchus mykiss) acclimated to 1, 5, and 10°C. At 10°C, the vessels showed a concentration-dependent dilation to adenosine (ADE; 61 ± 8%), sodium nitroprusside (SNP; 35 ± 10%), and serotonin (SER; 27 ± 2%) (all values maximum responses). A biphasic response (mild contraction then dilation) was observed in vessels exposed to increasing concentrations of epinephrine (EPI; 34 ± 9% dilation) and norepinephrine (NE; 32 ± 7% dilation), whereas the effect was less pronounced with bradykinin (BK; 12.5 ± 3.5% constriction vs. 6 ± 6% dilation). Finally, a mild constriction was observed after exposure to acetylcholine (ACh; 6.5 ± 1.4%), while endothelin (ET)-1 caused a strong dose-dependent increase in tone (79 ± 5% constriction). Acclimation temperature had varying effects on the responsiveness of vessels. The dilations induced by EPI, ADE, SER, and SNP were reduced/eliminated at 5°C and/or 1°C as compared with 10°C. In contrast, acclimation to 5 and 1°C increased the maximum constriction induced by ACh and the sensitivity of vessels to ET-1 (but not the maximum response) at 1°C was greater. Acclimation temperature had no effect on the response to NE, and responsiveness to BK was variable.
authors.affiliation: Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Canada; and.
authors.forename: Isabel A S F
authors.initials: IA
authors.lastname: Costa
authors.affiliation: Department of Surgery, College of Medicine, Texas A&M Health Science Center, Baylor Scott & White Health, Temple, Texas.
authors.forename: Travis W
authors.initials: TW
authors.lastname: Hein
authors.affiliation: Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Canada; and kgamperl@mun.ca.
authors.forename: A K
authors.initials: AK
authors.lastname: Gamperl
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D003080:Cold Temperature; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D008833:Microcirculation / Q000502:physiology*; D017686:Oncorhynchus mykiss / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents
keywords: cold; coronary; endothelium; hormones; microvessels; paracrine effects; vascular resistance; vascular tone; vasomotor responses