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The effect of temperature on cellular Ca + flux in ventricular myocytes from bluefin tuna
Author(s) -
Shiels Holly A,
Thompson S. H.,
Block B. A.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1239.28
Subject(s) - tuna , myocyte , endoplasmic reticulum , ryanodine receptor , thermocline , chemistry , biophysics , medicine , fishery , biology , biochemistry , ecology , fish <actinopterygii>
Bluefin Tuna ( Thunnus orientalis ) have the capacity to move from warm surface waters to cooler waters beneath the thermocline where they will be faced with the challenge of a cold heart delivering blood to metabolically warmed tissues. We used confocal microscopy to investigate the temporal and spatial characteristics of cellular Ca 2+ flux in bluefin tuna ventricular myocytes to further our understanding of the thermal tolerance of heart function in these animals. Tuna were acclimated to either 15°C or 23°C for a minimum of 3 weeks. Cardiac myocytes were isolated from the spongy myocardium and loaded with the Ca 2+ indicator dye Fluo‐4 and field‐stimulated to contract. Line scan images across the width of the myocyte revealed spatial inhomogeneities in the temporal properties of the Ca 2+ transients. The Ca 2+ wavefront initiated faster, rose faster and reached larger peak amplitude at the periphery of the cell compared with the centre. This pattern was exacerbated during acute cooling and when the sarcoplasmic reticulum was inhibited with ryanodine and thapsigargin.