Positive inotropism in hypothermia partially depends on an increase in maximal Ca2+-activated force

H. Kusuoka, Y. Ikoma, S. Futaki, H. Suga, A. Kitabatake, T. Kamada, M. Inoue

Research output: Contribution to journalArticle

Abstract

We investigated the contribution of maximal Ca2+-activated force to the positive inotropism induced by mild hypothermia. Phosphorus-31 nuclear magnetic resonance spectroscopy revealed that neither energy-related phosphorus compounds in myocardium nor intracellular pH was responsible for the change in contractility. Maximal Ca2+-activated pressure (MCAP), the intact-heart correlate of maximal Ca2+-activated force, was determined in isolated perfused rabbit hearts by measuring isovolumic left ventricular pressure during tetani at extracellular Ca2+ concentrations ≥ 10 mM. Tetani were elicited by rapid pacing after exposure to ryanodine. MCAP increased by 2.17 ± 0.28% (means ± SE, P <0.001, n = 19) for each degree of myocardial cooling between 30 and 38°C. Our results indicate that a primary change in myofilament Ca2+ responsiveness underlies the positive inotropism in hypothermia. The increase in maximal Ca2+-activated force may explain the observation of positive inotropism without an upward shift in the relation between oxygen consumption and pressure-volume area, as previously reported for cooled whole hearts.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume261
Issue number4 30-4
StatePublished - 1991
Externally publishedYes

Fingerprint

Muscle Contraction
Hypothermia
Tetanus
Pressure
Phosphorus Compounds
Induced Hypothermia
Ryanodine
Myofibrils
Ventricular Pressure
Oxygen Consumption
Phosphorus
Myocardium
Magnetic Resonance Spectroscopy
Observation
Rabbits

Keywords

  • excitation-contraction coupling
  • myofilament Ca responsiveness
  • phosphorus-31 nuclear magnetic resonance

ASJC Scopus subject areas

  • Physiology

Cite this

Kusuoka, H., Ikoma, Y., Futaki, S., Suga, H., Kitabatake, A., Kamada, T., & Inoue, M. (1991). Positive inotropism in hypothermia partially depends on an increase in maximal Ca2+-activated force. American Journal of Physiology - Heart and Circulatory Physiology, 261(4 30-4).

Positive inotropism in hypothermia partially depends on an increase in maximal Ca2+-activated force. / Kusuoka, H.; Ikoma, Y.; Futaki, S.; Suga, H.; Kitabatake, A.; Kamada, T.; Inoue, M.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 261, No. 4 30-4, 1991.

Research output: Contribution to journalArticle

Kusuoka, H, Ikoma, Y, Futaki, S, Suga, H, Kitabatake, A, Kamada, T & Inoue, M 1991, 'Positive inotropism in hypothermia partially depends on an increase in maximal Ca2+-activated force', American Journal of Physiology - Heart and Circulatory Physiology, vol. 261, no. 4 30-4.
Kusuoka, H. ; Ikoma, Y. ; Futaki, S. ; Suga, H. ; Kitabatake, A. ; Kamada, T. ; Inoue, M. / Positive inotropism in hypothermia partially depends on an increase in maximal Ca2+-activated force. In: American Journal of Physiology - Heart and Circulatory Physiology. 1991 ; Vol. 261, No. 4 30-4.
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AU - Ikoma, Y.

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AU - Kitabatake, A.

AU - Kamada, T.

AU - Inoue, M.

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