{"doi":"10.17615/yxsq-jw30","title":"Mitochondrial Calcium Transients in Adult Rabbit Cardiac Myocytes: Inhibition by Ruthenium Red and Artifacts Caused by Lysosomal Loading of Ca2+-Indicating Fluorophores","abstract":"A cold/warm loading protocol was used to ester-load Rhod 2 into mitochondria and other organelles and Fluo 3 into the cytosol of adult rabbit cardiac myocytes for confocal fluorescence imaging. Transient increases in both cytosolic Fluo 3 and mitochondrial Rhod 2 fluorescence occurred after electrical stimulation. Ruthenium red, a blocker of the mitochondrial Ca(2+) uniporter, inhibited mitochondrial Rhod 2 fluorescence transients but not cytosolic Fluo 3 transients. Thus the ruthenium red-sensitive mitochondrial Ca(2+) uniporter catalyzes Ca(2+) uptake during beat-to-beat transients of mitochondrial free Ca(2+), which in turn may help match mitochondrial ATP production to myocardial ATP demand. After ester loading, substantial amounts of Ca(2+)-indicating fluorophores localized into an acidic lysosomal/endosomal compartment. This lysosomal fluorescence did not respond to electrical stimulation. Because fluorescence arose predominantly from lysosomes after the cold loading/warm incubation procedure, total cellular fluorescence failed to track beat-to-beat changes of mitochondrial fluorescence. Only three-dimensionally resolved confocal imaging distinguished the relatively weak mitochondrial signal from the bright lysosomal fluorescence.","journal":"UNC Libraries","year":2020,"id":138838,"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":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9447,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":267321,"name":"Wayne E. Cascio","orcid":"0000-0003-1360-8093","position":1,"is_corresponding":false},{"id":342793,"name":"John J. Lemasters","orcid":"0000-0002-7627-6295","position":2,"is_corresponding":false},{"id":601498,"name":"Donna R. Trollinger","orcid":null,"position":0,"is_corresponding":true}],"reference_count":0,"raw_metadata":null,"created_at":"2026-07-18T23:17:06.651725Z","pmid":null,"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":[]}