Vascular reactivity of the coronary artery in rainbow trout (Oncorhynchus mykiss)

Abstract

Vascular reactivity of the large coronary artery of a lower vertebrate was investigated for the first time in this study. The responses of vascular rings to various pharmacological agents were measured using isometric force transducers. Coronary arteries from rainbow trout, Oncorhynchus mykiss, contracted with acetylcholine and predominantly relaxed with isoproterenol, epinephrine, norepinephrine, and serotonin. Atenolol blocked the adrenergic relaxation, suggesting a predominance of beta 1-adrenoceptors. Nitroglycerin and sodium nitroprusside relaxed vascular rings. Responses to histamine and bradykinin were absent in this tissue. Adenosine, ADP, and ATP caused contractions that could be blocked by theophylline. The difference in vascular reactivity between that typically found in mammalian coronary arteries and that reported here for rainbow trout are discussed.

Role of NO in arterial vascular function of intertidal fish (Girella laevifrons) and marine fish (Isacia conceptionis)

“…Higher vasoconstriction to acetylcholine was observed in ABA and EBA in I. conceptionis in comparison with G. laevifrons, and a minor effect of blockade with indomethacine in the maximum response to acetylcholine was observed in ABA and DA vessels in I. conceptionis as compared to G. laevifrons. In general, the results obtained in both of these species are partially in agreement with previous studies performed in species of great phylogenetic distance (agnathes, elasmobranches, teleost), that showed that acetylcholine induced contraction (Small et al, 1990;Miller and Vanhoutte, 1992;Evans and Gunderson, 1998a). However, the Ach-mediated vasoconstriction described in our study suggests that the coupled Ach-COX contraction produced when there is a decreased availability of nitric oxide (NO) is similar to that reported in human hypertension or hypertension models in rats (Vanhoutte et al, 2005;Shi et al, 2008).…”

“…the same authors describe that this vasoconstriction was abolished by the use of atropine (10 -5 M). This evidence has been corroborated by other studies in trout, shark and eel (Nilsson and Grove, 1974;Pellegrino et al, 2003;Pellegrino et al, 2002;Small et al, 1990), supporting the presence of muscarinic receptors in fish vasculature.…”

“…In general, NO is generated by nitric oxide synthase (NOS) located in the vascular endothelium, nitrinergic nerves and macrophages in endothelium (Furchgott and Zawadzki, 1980;Griffith et al, 1984;Toda and Okamura, 2003;Donald and Broughton, 2005), and its production is coupled with stimulation by the Ach-NOS-NO-relaxation pathway. In contrast, several studies have described that this pathway is uncoupled in elasmobranches and teleost fishes (Small et al, 1990;Miller and Vanhoutte, 1992;Evans and Gunderson, 1998b). Our objective was to evaluate the role of the acetylcholine-NO pathway by blockade with L-NAME, and the dilator role of NO using sodium nitroprusside (NO donor) in the arterial vessel of dorsal, mesenteric, branchial afferent and branchial efferent arteries from the intertidal fish G. laevifrons and marine fish I. conceptionis.…”

The effects of purine compounds on the isolated aorta of the frog Rana temporaria

“…The vasodilator activity of adenosine in the frog aorta is consistent with its vasodilator action in both mammals (see Burnstock, 1990b) and fish vessels, including the trout and skate coronary arteries (Small et al, 1990;Farrell & Davie, 1991) and dogfish aorta (Meghji & Burnstock, 1984). In mammals the subclass of P1-purinoceptor mediating vasodilatation of most vessels is the A2-receptor (Burnstock, 1990b).…”

“…Studies have revealed PI-purinoceptors on the coronary artery of trout and skate (Small et al, 1990;Farrell & Davie, 1991) and trout gill vasculature , dogfish atria and aorta (Meghji & Burnstock, 1984;Evans, 1992). ATP has been shown to dilate the portal vein of the lizard (Ojewole, 1983).…”