The effect of ryanodine on isometric tension development in isolated ventricular trabeculae from Pacific mackerel (Scomber japonicus)

H. A. Shiels, A. P. Farrell

    Research output: Contribution to journalArticlepeer-review

    Abstract

    An isometric muscle preparation was used to study the inhibitory effect of ryanodine on contractile function in isolated ventricular trabeculae of the Pacific mackerel (Scomber japonicus). Ryanodine (an inhibitor of sarcoplasmic reticulum (SR) function) caused a 20% reduction in peak tension at 20°C, but not 15°C, over the range of frequencies (0.2-3.0 Hz) tested. This indicates that in the absence of a functional SR, the mackerel ventricle can maintain most of its contractile strength utilizing other modes of Ca2+ delivery to the myofilaments. Ca2+ flux through the sarcolemmal (SL) L-type Ca2+-channels is most likely the predominant pathway for Ca2+ activation of the myofilaments, although reverse mode Na+/Ca2+ exchange could potentially contribute to a significant extent. High levels of adrenergic stimulation overwhelmed the negative inotropy caused by ryanodine, returning tension to pre-ryanodine levels, further suggesting that the mackerel ventricle can maintain contractile function without Ca2+ contribution from the SR. These results are discussed within the context of what is known about SR Ca2+ utilization in rainbow trout and tuna hearts. Copyright (C) 2000 Elsevier Science Inc.
    Original languageEnglish
    Pages (from-to)331-341
    Number of pages10
    JournalComparative Biochemistry and Physiology. Part A: Molecular & Integrative Physiology
    Volume125
    Issue number3
    DOIs
    Publication statusPublished - Mar 2000

    Keywords

    • Adrenaline
    • Cardiac physiology
    • Force-frequency
    • Pacific mackerel (Scomber japonicus)
    • Ryanodine
    • Sarcoplasmic reticulum (SR)
    • Scombrid physiology
    • Temperature
    • Ventricle

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