Responsiveness of Contractile Elements to Muscle Length Change in Hyperthyroid Ferret Myocardium

  • Tetsuya Ishikawa
  • Hidetoshi Kajiwara
  • Seibu Mochizuki
  • Satoshi Kurihara
Part of the Progress in Experimental Cardiology book series (PREC, volume 3)

Summary

Hyperthyroidism induces cardiac hypertrophy, which alters the properties of contractile elements. However, the responsiveness of hyperthyroid myocardium to changes in muscle length (the cellular basis of Frank-Starling’s law of the heart) is poorly understood. In the present study, we measured the changes in tension and the Ca2+ transients monitored with aequorin in the papillary muscles excised from thyroxine-treated hyperthyroid ferrets (Hy) when muscle length was quickly changed during twitch contraction. We also measured the pCa-tension relationship at different muscle lengths in trabeculae treated with Triton X-100. The ratio of heart weight to body weight in Hy was significantly higher than that in age-matched euthyroid ferrets (Eu) (p < 0.001). Extra-Ca2+ (a transient increase in the intracellular Ca + concentration in response to quick length change) did not significantly differ in Hy and Eu. The values of pCa50 reflecting the responsiveness of the myofilament to Ca2+, measured at sarcomere lengths of 2.3 and 1.9 µm, were identical at each sarcomere length in Hy and Eu. These results indicate that in the hypertrophied mycoardium induced by hyperthyroidism the responsiveness of the contractile elements to muscle length change is similar to that in euthyroid myocardium.

Keywords

Methane Magnesium Platinum HEPES Creatine 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Klein I. 1990. Thyroid hormone and the cardiovascular system. Am J Med 88:631–637.PubMedCrossRefGoogle Scholar
  2. 2.
    Ishikawa T, Kajiwara H, Kurihara S. In press. Modulation of the Ca2+ transient decay by tension and Ca2+ removal in hyperthyroid myocardium. Am J Physiol 276:H289–H299.Google Scholar
  3. 3.
    Allen DG, Kurihara S. 1982. The effects of muscle length on intracellular calcium transients in mammalian cardiac muscle. J Physiol (Lond) 327:79–94.Google Scholar
  4. 4.
    Okazaki O, Suda N, Hongo K, Konishi M, Kurihara S. 1990. Modulation of Ca2+ transients and contractile properties by β-adrenoceptor stimulation in ferret ventricular muscles. J Physiol (Lond) 423:221–240.Google Scholar
  5. 5.
    Komukai K, Ishikawa T, Kurihara S. 1998. Effects of acidosis on Ca2+ sensitivity of contractile elements in intact ferret myocardium. Am J Physiol 274:H147–H154.PubMedGoogle Scholar
  6. 6.
    Kurihara S, Komukai K. 1995. Tension-dependent changes of the intracellular Ca2+ transients in ferret ventricular muscles. J Physiol (Lond) 489:617–625.Google Scholar
  7. 7.
    Kurihara S, Saeki Y, Hongo K, Tanaka E, Suda N. 1990. Effects of length change on intracellular Ca2+ transients in ferret ventricular muscle treated with 2,3-butanedione monoxine (BDM). Jpn J Physiol 40:915–920.PubMedCrossRefGoogle Scholar
  8. 8.
    Horiuti K. 1986. Bioassay of calcium in skinned smooth muscle by contraction of skinned skeletal muscle placed nearby. Jikeikai Med J 33:149–156.Google Scholar
  9. 9.
    Martell AE, Smith RM. 1994. Critical Stability Constants. Vol. 1. Amino Acids. New York: Plenum.Google Scholar
  10. 10.
    MacKinnon R, Gwathmey JK, Allen PD, Briggs GM, Morgan JP. 1988. Modulation by the thyroid state of intracellular calcium and contractility in ferret ventricular muscle. Circ Res 63:1080–1089.PubMedCrossRefGoogle Scholar
  11. 11.
    Fitzsimons DP, Patel JR, Moss RL. 1998. Role of myosin heavy chain composition in kinetics of force development and relaxation in rat myocardium. J Physiol 513:171–183.PubMedCrossRefGoogle Scholar
  12. 12.
    Kiss E. Jakab G, Kranias EG, Edes I. 1994. Thyroid hormone-induced alterations in phospholamban protein expression. Circ Res 75:245–251.PubMedCrossRefGoogle Scholar
  13. 13.
    Rossmanith GH, Hoh JFY, Kirman A, Kwan J. 1986. Influence of V1 and V3 isomyosins on the mechanical behaviour of rat papillary muscle as studied by pseudo-random binary noise modulated length perturbations. J Muscle Res Cell Motil 7:307–319.PubMedCrossRefGoogle Scholar
  14. 14.
    Fuchs F, Wang YP. 1996. Sarcomere length versus interfilament lattice spacing as determinants of cardiac myofilament Ca2+ sensitivity and Ca2+ binding. J Mol Cell Cardiol 28:1375–1383.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2000

Authors and Affiliations

  • Tetsuya Ishikawa
    • 1
  • Hidetoshi Kajiwara
    • 1
  • Seibu Mochizuki
    • 1
  • Satoshi Kurihara
    • 2
  1. 1.Department of PhysiologyThe Jikei University School of MedicineMinato-ku, TokyoJapan
  2. 2.Department of CardiologyThe Jikei University School of MedicineMinato-ku, TokyoJapan

Personalised recommendations