Stretch and quick release of rat cardiac trabeculae accelerates Ca2+ waves and triggered propa gated contractions

Yuji Wakayama, Masahito Miura, Yoshinao Sugai, Yutaka Kagaya, J. U.N. Watanabe, Henk E.D.J. Ter Keurs, Kunio Shirato

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)

Abstract

Rapid shortening of active cardiac muscle [quick release (QR)] dissociates Ca2+ from myofilaments. We studied, using muscle stretches and QR, whether Ca2+ dissociation affects triggered propagated contractions (TPCs) and Ca2+ waves. The intracellular Ca2+ concentration was measured by a SIT camera in right ventricular trabeculae dissected from rat hearts loaded with fura 2 salt, force was measured by a silicon strain gauge, and sarcomere length was measured by laser diffraction while a servomotor controlled muscle length. TPCs (n = 27) were induced at 28°C by stimulus trains (7.5 s at 2.65 ± 0.13 Hz) at an extracellular Ca2+ concentration ([Ca2+]o) = 2.0 mM or with 10 μM Gd3+ at [Ca2+]o = 5.2 ± 0.73 mM. QR during twitch relaxation after a 10% stretch for 100-200 ms reduced both the time between the last stimulus and the peak TPC (PeakTPC) and the time between the last stimulus and peak Ca2+ wave (Peakcw) and increased PeakTPC and PeakCW (n = 13) as well as the propagation velocity (Vprop; n = 8). Active force during stretch also increased Vprop (r = 0.84, n = 12, P < 0.01), but Gd3+ had no effect (n = 5). These results suggest that Ca2+ dissociation by QR during relaxation accelerates the initiation and propagation of Ca2+ waves.

Original languageEnglish
Pages (from-to)H2133-H2142
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume281
Issue number5 50-5
DOIs
Publication statusPublished - 2001

Keywords

  • Arrhythmias

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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