To excite a heart: A bird's view

J. R. Sommer, E. Bossen, H. Dalen, P. Dolber, T. High, P. Jewett, E. A. Johnson, J. Junker, S. Leonard, R. Nassar, B. Scherer, M. Spach, T. Spray, I. Taylor, N. R. Wallace, R. Waugh

    Research output: Contribution to journalArticle

    13 Scopus citations

    Abstract

    Ultrastructural investigations of avian cardiac muscle, including ratite hearts, have provided great insights into the mechanisms as to how excitation leads to contraction in the heart. The geometry of the conduction fibers of ratite hearts confirm earlier observations on birds showing that the geometry of the conduction system and its component cells is adapted to hearts of different sizes and rates of contraction so as to maintain a differential in conduction velocities between the conduction system and the working fibers. The study of the ratite conduction fibers bears out the idea of an inverse relationship between the size of the gap junctions and the input resistance of cardiac cells. The anomalous extended junctional SR typical of all avian hearts, proscribes the notion of direct contact transduction into calcium release for contraction of an excitatory signal propagating at the cell surface. Couplings appear well suited to maintain direct, if transitory, connections to the extracellular space in addition to harboring channels for intracellular calcium release.

    Original languageEnglish (US)
    Pages (from-to)5-21
    Number of pages17
    JournalActa Physiologica Scandinavica, Supplement
    Volume142
    Issue number599
    StatePublished - Jan 1 1991

    ASJC Scopus subject areas

    • Physiology

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  • Cite this

    Sommer, J. R., Bossen, E., Dalen, H., Dolber, P., High, T., Jewett, P., Johnson, E. A., Junker, J., Leonard, S., Nassar, R., Scherer, B., Spach, M., Spray, T., Taylor, I., Wallace, N. R., & Waugh, R. (1991). To excite a heart: A bird's view. Acta Physiologica Scandinavica, Supplement, 142(599), 5-21.