eprintid: 20159 rev_number: 39 eprint_status: archive userid: 14001 dir: disk0/00/02/01/59 datestamp: 2009-12-19 16:01:06 lastmod: 2025-05-01 13:49:52 status_changed: 2009-12-19 16:01:06 type: article metadata_visibility: show item_issues_count: 0 creators_name: Loughrey, C.M. creators_name: MacEachern, K.E. creators_name: Neary, P. creators_name: Smith, G.L. creators_orcid: 0000-0003-1297-9159 creators_orcid: 0000-0002-7705-6956 creators_orcid: 0000-0003-4821-9741 title: The relationship between intracellular [Ca²⁺] and Ca²⁺ wave characteristics in permeabilised cardiomyocytes from the rabbit ispublished: pub divisions: 25200000 divisions: 20300000 abstract: Spontaneous sarcoplasmic reticulum (SR) Ca2+ release and propagated intracellular Ca2+ waves are a consequence of cellular Ca2+ overload in cardiomyocytes. We examined the relationship between average intracellular [Ca2+] and Ca2+ wave characteristics. The amplitude, time course and propagation velocity of Ca2+ waves were measured using line-scan confocal imaging of beta-escin-permeabilised cardiomyocytes perfused with 10 muM Fluo-3 or Fluo-5F. Spontaneous Ca2+ waves were evident at cellular [Ca2+] > 200 nm. Peak [Ca2+] during a wave was 2.0-2.2 muM; the minimum [Ca2+] between waves was 120-160 nm; wave frequency was similar to0.1 Hz. Raising mean cellular [Ca2+] caused increases in all three parameters, particularly Ca2+ wave frequency. Increases in the rate of SR Ca2+ release and Ca2+ uptake were observed at higher cellular [Ca2+], indicating calcium-sensitive regulation of these processes. At extracellular [Ca2+] > 2 muM, the mean [Ca2+] inside the permeabilised cell did not increase above 2 muM. This extracellular-intracellular Ca2+ gradient could be maintained for periods of up to 5 min before the cardiomyocyte developed a sustained and irreversible hypercontraction. Inclusion of mitochondrial inhibitors (2 muM carbonyl cyanide m-chlorophenylhydrazone and 2 muM oligomycin) while perfusing with > 2 muM Ca2+ abolished the extracellular-intracellular Ca2+ gradient through the generation of Ca2+ waves with a higher peak [Ca2+] compared to control conditions. Under these conditions, cardiomyocytes rapidly (< 2 min) developed a sustained and irreversible contraction. These results suggest that mitochondrial Ca2+ uptake acts to delay an increase in [Ca2+] 1 by blunting the peak of the Ca2+ wave. date: 2002-09 date_type: published id_number: 10.1113/jphysiol.2002.021519 uniqueid: glaseprints:2002-20159 thomson_ut: 178374300012 published_online: 2002-07-12 issn_online: 1469-7793 scopus_impact: 19 scopus_cluster: 2-s2.0-0037106291 scopus_datestamp: 2013-10-25 19:58:12 wos_impact: 22 wos_cluster: WOS:000178374300012 wos_datestamp: 2013-10-24 21:12:55 pubmed_id: 12231644 euro_pubmed_id: 12231644 legacy_divisions: L20300000 full_text_status: none publication: Journal of Physiology volume: 543 number: 3 pagerange: 859-870 refereed: TRUE issn: 0022-3751 hoa_compliant: 305 hoa_date_acc: 2002-07-12 hoa_date_pub: 2002-07-22 hoa_exclude: FALSE hoa_gold: FALSE citation: Loughrey, C.M. , MacEachern, K.E. , Neary, P. and Smith, G.L. (2002) The relationship between intracellular [Ca2+] and Ca2+ wave characteristics in permeabilised cardiomyocytes from the rabbit. Journal of Physiology , 543(3), pp. 859-870. (doi: 10.1113/jphysiol.2002.021519 ) (PMID:12231644)