{"doi":"10.1016/j.crphys.2022.01.001","title":"The air-breathing Alaska blackfish (Dallia pectoralis) remodels ventricular Ca2+ cycling with chronic hypoxic submergence to maintain ventricular contractility","abstract":"The Alaska blackfish (Dallia pectoralis) is a facultative air-breather endemic to northern latitudes where it remains active in winter under ice cover in cold hypoxic waters. To understand the changes in cellular Ca2+ cycling that allow the heart to function in cold hypoxic water, we acclimated Alaska blackfish to cold (5 °C) normoxia or cold hypoxia (2.1–4.2 kPa; no air access) for 5–8 weeks. We then assessed the impact of the acclimation conditions on intracellular Ca2+ transients (Δ[Ca2+]i) of isolated ventricular myocytes and contractile performance of isometrically-contracting ventricular strips. Measurements were obtained at various contractile frequencies (0.2–0.6 Hz) in normoxia, during acute exposure to hypoxia, and reoxygenation at 5 °C. The results show that hypoxia-acclimated Alaska blackfish compensate against the depressive effects of hypoxia on excitation-contraction coupling by remodelling cellular Δ[Ca2+]i to maintain ventricular contractility. When measured at 0.2 Hz in normoxia, hypoxia-acclimated ventricular myocytes had a 3.8-fold larger Δ[Ca2+]i peak amplitude with a 4.1-fold faster rate of rise, compared to normoxia-acclimated ventricular myocytes. At the tissue level, maximal developed force was 2.1-fold greater in preparations from hypoxia-acclimated animals. However, maximal attainable contraction frequencies in hypoxia were lower in hypoxia-acclimated myocytes and strips than preparations from normoxic animals. Moreover, the inability of hypoxia-acclimated ventricular myocytes and strips to contract at high frequency persisted upon reoxygenation. Overall, the findings indicate that hypoxia alters aspects of Alaska blackfish cardiac myocyte Ca2+ cycling, and that there may be consequences for heart rate elevation during hypoxia, which may impact cardiac output in vivo.","journal":"Current Research in Physiology","year":2022,"id":281067,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":8,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.957,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":955914,"name":"Ed White","orcid":"0000-0002-3954-9792","position":1,"is_corresponding":false},{"id":430357,"name":"Christine S. Couturier","orcid":"0000-0003-3417-3906","position":2,"is_corresponding":false},{"id":431307,"name":"Diarmid Hall","orcid":null,"position":3,"is_corresponding":false},{"id":956368,"name":"Shannon Royal","orcid":null,"position":4,"is_corresponding":false},{"id":955915,"name":"Gina L. J. Galli","orcid":"0000-0002-1023-915X","position":5,"is_corresponding":false},{"id":430356,"name":"Jonathan A. W. Stecyk","orcid":"0000-0002-0973-9472","position":6,"is_corresponding":false},{"id":955913,"name":"Holly A. Shiels","orcid":"0000-0001-5223-5205","position":0,"is_corresponding":true}],"reference_count":55,"raw_metadata":null,"created_at":"2026-07-19T00:29:07.472902Z","pmid":"35072107","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}