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|Title:||Cardiophysiological responses of the air-breathing Alaska blackfish to cold acclimation and chronic hypoxic submergence at 5°C|
|Authors:||Stecyk, J. A. W.|
Couturier, C. S.
Abramochkin, D. V.
Kubly, K. L.
|Publisher:||Company of Biologists Ltd|
|Citation:||Cardiophysiological responses of the air-breathing Alaska blackfish to cold acclimation and chronic hypoxic submergence at 5°C / J. A. W. Stecyk, C. S. Couturier, D. V. Abramochkin, et al. — DOI 10.1242/jeb.225730 // Journal of Experimental Biology. — 2020. — Vol. 223. — Iss. 22. — jeb225730.|
|Abstract:||The Alaska blackfish (Dallia pectoralis) remains active at cold temperatures when experiencing aquatic hypoxia without air access. To discern the cardiophysiological adjustments that permit this behaviour, we quantified the effect of acclimation from 15°C to 5°C in normoxia (15N and 5N fish), as well as chronic hypoxic submergence (6-8 weeks; ∼6.3-8.4 kPa; no air access) at 5°C (5H fish), on in vivo and spontaneous heart rate (fH), electrocardiogram, ventricular action potential (AP) shape and duration (APD), the background inward rectifier (IK1) and rapid delayed rectifier (IKr) K+ currents and ventricular gene expression of proteins involved in excitation-contraction coupling. In vivo fH was ∼50% slower in 5N than in 15N fish, but 5H fish did not display hypoxic bradycardia. Atypically, cold acclimation in normoxia did not induce shortening of APD or alter resting membrane potential. Rather, QT interval and APD were ∼2.6-fold longer in 5N than in 15N fish because outward IK1 and IKr were not upregulated in 5N fish. By contrast, chronic hypoxic submergence elicited a shortening of QT interval and APD, driven by an upregulation of IKr. The altered electrophysiology of 5H fish was accompanied by increased gene expression of kcnh6 (3.5-fold; Kv11.2 of IKr), kcnj12 (7.4-fold; Kir2.2 of IK1) and kcnj14 (2.9-fold; Kir2.4 of IK1). 5H fish also exhibited a unique gene expression pattern that suggests modification of ventricular Ca2+ cycling. Overall, the findings reveal that Alaska blackfish exposed to chronic hypoxic submergence prioritize the continuation of cardiac performance to support an active lifestyle over reducing cardiac ATP demand. © 2020. Published by The Company of Biologists Ltd|
|metadata.dc.description.sponsorship:||This research was funded by the National Science Foundation, Division of Integrative Organismal Systems (1557818) and UAA Innovate Award (J.A.W.S.); the Russian Science Foundation (19-15-00163) (D.V.A.); Alaska INBRE (IDeA Network of Biomedical Research Excellence from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20GM103395; the content is solely the responsibility of the authors and does not necessarily reflect the official views of the NIH) and LGL Limited Environmental Research Associates graduate research awards (K.L.K.). Deposited in PMC for release after 12 months.|
|RSCF project card:||19-15-00163|
|Appears in Collections:||Научные публикации, проиндексированные в SCOPUS и WoS CC|
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