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

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.

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Effects of polyunsaturated fatty acids and some of their metabolites on mitotic activity of vascular smooth muscle explants from the coronary artery of rainbow trout (Oncorhynchus mykiss)

Canadian Journal of Zoology ◽

10.1139/z97-710 ◽

1997 ◽

Vol 75 (1) ◽

pp. 80-86 ◽

Cited By ~ 8

Author(s):

B. Gong ◽

R. Townley ◽

A. P. Farrell

Keyword(s):

Fatty Acids ◽

Smooth Muscle ◽

Rainbow Trout ◽

Coronary Artery ◽

Vascular Smooth Muscle ◽

Polyunsaturated Fatty Acids ◽

Oncorhynchus Mykiss ◽

Thymidine Incorporation ◽

Mitogenic Effect ◽

Rainbow Trout Oncorhynchus Mykiss

This study is the first to examine the effects of polyunsaturated fatty acids and some of their metabolites on [3H]thymidine incorporation into vascular smooth muscle explants from the coronary artery of rainbow trout (Oncorhynchus mykiss). At a concentration of 120 μM, eicosapentaenoic acid (EPA; 20:5ω3), arachidonic acid (AA; 20:4ω6), and eicosatrienoic acid (ETA; 20:3ω6) all approximately doubled [3H]thymidine incorporation relative to controls. At a concentration of 20 μM, EPA had no significant effect, while ETA inhibited and AA caused an almost 5-fold increase in [3H]thymidine incorporation. The large mitogenic effect of 20 μM AA was completely inhibited by simultaneous addition of EPA to the culture medium. ETA only partially inhibited the mitogenic effect of 20 μM AA. Four AA-derived eicosanoids (or their stable analogues) were also tested. [3H]Thymidine incorporation was at least doubled with 1000 ng/mL carbacyclin (a prostacyclin analogue), 120 ng/mL prostaglandin F2α, and U-46619 (a thromboxane A2 analogue), but did not reach the level of stimulation produced by 20 μM AA. Leukotriene C4 had no significant effect. We conclude that dietary modulation of polyunsaturated fatty acids (PUFAs) in salmonids could have significant effects on coronary vascular smooth muscle mitosis through the incorporation of PUFAs into cell membranes and the production of eicosanoids.

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Effects of exercise training and coronary ablation on swimming performance, heart size, and cardiac enzymes in rainbow trout, Oncorhynchus mykiss

Canadian Journal of Zoology ◽

10.1139/z90-174 ◽

1990 ◽

Vol 68 (6) ◽

pp. 1174-1179 ◽

Cited By ~ 87

Author(s):

A. P. Farrell ◽

J. A. Johansen ◽

J. F. Steffensen ◽

C. D. Moyes ◽

T. G. West ◽

...

Keyword(s):

Rainbow Trout ◽

Coronary Artery ◽

Oncorhynchus Mykiss ◽

Citrate Synthase ◽

Swimming Performance ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Coronary Ligation ◽

Heart Mass ◽

Hydroxyacyl Coa Dehydrogenase ◽

Exercise Induced

Rainbow trout, Oncorhynchus mykiss, were exercise trained for 28–52 days. Trained fish were 13% larger and swam 12% faster in an aerobic swimming test. Training induced cardiac growth that was isometric with body growth, since ventricle mass relative to body mass was constant. The proportions of compact and spongy myocardia in the ventricle were also unchanged by training. Trained fish had significantly higher levels of citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase in both compact and spongy myocardium. Ligation of a 0.5- to 1.0-cm section of the coronary artery produced only a temporary interruption of coronary flow to the compact myocardium because new vessels grew around the ligation site in the majority of fish during the 28- to 52-day experiment. Nonetheless, coronary ligation resulted in a significantly smaller (17%) proportion of compact myocardium with lower levels of citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase. Exercise-induced increases in the levels of these enzymes in the compact myocardium were prevented by coronary ligation. The decrease of enzymes in the compact myocardium as a result of coronary ligation was compensated for by a 30% increase in the levels of the aerobic enzymes citrate synthase and β-hydroxyacyl CoA dehydrogenase and a 32% increase in the mass of spongy myocardium. As a result of these compensations and coronary regrowth, chronic coronary ligation did not affect maximum prolonged swimming speed. These experiments clearly reveal that cardiac plasticity allows compensatory changes that are necessary for the heart to maintain adequate oxygen delivery to exercising skeletal muscle. The compensatory changes were isometric increases in heart mass or proportionately larger increases in heart mass and compact tissue if the coronary artery was ligated and an increase in metabolic enzymes associated with ATP generation, namely, citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase.

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It takes time to heal a broken heart: Ventricular plasticity improves heart performance after myocardial infarction in rainbow trout, Oncorhynchus mykiss

Journal of Experimental Biology ◽

10.1242/jeb.243578 ◽

2021 ◽

Author(s):

Lucas A. Zena ◽

Andreas Ekström ◽

Albin Gräns ◽

Catharina Olsson ◽

Michael Axelsson ◽

...

Keyword(s):

Heart Rate ◽

Rainbow Trout ◽

Coronary Artery ◽

Oncorhynchus Mykiss ◽

Coronary Occlusion ◽

Morphological Characteristics ◽

Coronary Artery Ligation ◽

Resting Heart Rate ◽

Rainbow Trout Oncorhynchus Mykiss

Coronary arteriosclerosis is a common feature of both wild and farmed salmonid fishes and may be linked to stress-induced cardiac pathologies. Yet, the plasticity and capacity for long-term myocardial restructuring and recovery following a restriction in coronary blood supply is unknown. Here, we analyzed the consequences of acute (3 days) and chronic (from 33 to 62 days) coronary occlusion (i.e., coronary artery ligation) on cardiac morphological characteristics and in vivo function in juvenile rainbow trout, Oncorhynchus mykiss. Acute coronary occlusion resulted in elevated resting heart rate and decreased inter-beat variability, which are both markers of autonomic dysfunction following acute myocardial ischemia, along with severely reduced heart rate scope (maximum – resting heart rate) relative to sham-operated trout. We also observed a loss of myocardial interstitial collagen and compact myocardium. Following long-term coronary- ligation, resting heart rate and heart rate scope normalized relative to sham-operated trout. Moreover, a distinct fibrous collagen layer separating the compact myocardium into two layers had formed. This may contribute to maintain ventricular integrity across the cardiac cycle, or alternatively, demark a region of the compact myocardium that continues to receive oxygen from the luminal venous blood. Taken together, we demonstrate that rainbow trout may cope with the aversive effects caused by coronary artery obstruction through plastic ventricular remodeling, which, at least in part, restores cardiac performance and myocardium oxygenation.

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