Characterization of Junctional Sarcoplasmic Reticulum Ca2+ Content and Release by Short-Term Mechanical Restitution in Cardiac Muscle

DOI Web Site Web Site PubMed 被引用文献1件 参考文献49件
  • Tameyasu T.
    Department of Physiology, St. Marianna University School of Medicine
  • Tanaka M.
    Department of Physiology, St. Marianna University School of Medicine
  • Ogura S.
    Department of Physiology, St. Marianna University School of Medicine
  • Sato M.
    Department of Physiology, St. Marianna University School of Medicine

書誌事項

タイトル別名
  • Characterization of Junctional Sarcoplasmic Reticulum Ca<sup>2+</sup> Content and Release by Short-Term Mechanical Restitution in Cardiac Muscle

この論文をさがす

抄録

To study Ca2+ handling by the junctional sarcoplasmic reticulum (JSR), the time course of short-term mechanical restitution after varying magnitudes of twitch contractions was assessed in rat papillary muscle. Mechanical restitution consisted of a pretwitch latency period followed by a rapid and a subsequent much slower restitution of twitch force. The rate of rapid restitution was independent of the magnitude of the preceding twitch, which suggests that the rate of JSR Ca2+ repletion was dependent on the amount of Ca2+ remaining in the JSR after a twitch contraction. Based on this finding, the functions G(t) and H(t), representing the time courses of JSR Ca2+ repletion and release, respectively, were derived graphically from a family of the mechanical restitution curves. G(t) increased monotonically with time at a decreasing rate, while H(t) increased with time in a sigmoid manner. The mechanical alternans were simulated by using experimental values and mathematically predicted values of G(t) and H(t). A substitution of extracellular Na+ with Li+ to inhibit Na+/Ca2+ exchange resulted in an augmentation of G(t) by approximately 10%, presumably by increasing the tubular SR Ca2+ uptake. The inhibition of tubular SR Ca2+ uptake by thapsigargin (10 μM) reduced mechanical restitution by approximately 13% of the maximal twitch force, independent of the phase of mechanical restitution; the effect was greater at an earlier time point in the mechanical restitution. These results suggest that early JSR Ca2+ replenishment results mainly from the movement of Ca2+ from the tubular SR.<br>

収録刊行物

被引用文献 (1)*注記

もっと見る

参考文献 (49)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ