Summary
Isolated atrial and ventricular preparations from rat heart have been compared. In atrial specimens relaxation is faster than in papillary muscles both in isometric and isotonic conditions. In papillary muscles the tension decay occurs earlier in isotonic than isometric contractions and a stretch applied at or after the peak of isometric twitches promotes a faster relaxation: this load dependence of relaxation is less pronounced in atrial specimens. The decay of activation, evaluated from the decline of the muscle shortening ability, is faster in atrium than in ventricle. These findings suggest that the sensitivity of relaxation to the loading conditions might be determined by both the activation decay rate and the cross bridge kinetics.
Zusammenfassung
In der vorliegenden Arbeit wird die Mechanik isolierter Muskelpräparate vom Vorhof und Ventrikel des Rattenherzens verglichen. Bei Vorhofpräparaten beginnt der Erschlaffungsprozeß unter isometrischen und isotonischen Bedingungen früher als beim Papillarmuskel. Bei Papillarmuskeln tritt der Abfall der Spannung unter isotonischen Bedingungen früher in Erscheinung als bei isometrischen Kontraktionen; eine Streckung zum Zeitpunkt der isometrischen Gipfelzeit oder danach verursacht schnellere Erschlaffung. Diese Abhängigkeit der Erschlaffung von der Last ist bei Vorhofpräparaten weniger ausgeprägt. Der Rückgang der Aktivierung, bewertet aufgrund der abnehmenden Verkürzungsfähigkeit des Muskels, erfolgt beim Vorhof schneller als beim Ventrikel. Die Ergebnisse lassen vermuten, daß die Abhängigkeit der Erschlaffung von den Belastungsbedingungen sowohl durch die Geschwindigkeit des Aktivierungsrückgangs als auch durch die Querbrückenkinetik bestimmt wird.
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References
Abbott, B. C., W. F. H. M. Mommaerts: A study of inotropic mechanisms in the papillary muscle preparation. J. Gen. Physiol.42, 533–551 (1959).
Bodem, R., E. H. Sonnenblick: Deactivation of contraction by quick releases in the isolated papillary muscle of the cat. Circulat. Res.34, 214–225 (1974).
Brady, A. J.: Onset of contractility in cardiac muscle. J. Physiol. (London)184, 560–580 (1966).
Brutsaert, D. L., N. M. De Clerck, M. A. Goethals, P. R. Housmans: Relaxation of ventricular cardiac muscle. J. Physiol. (London)283, 469–480 (1978).
Couttenye, M. M., N. M. De Clerck, M. A. Goethals, D. L. Brutsaert: Relaxation properties of mammalian atrial muscle. Circulat. Res.48, 352–356 (1981).
Dhalla, N. S., P. V. Sulakhe, S. L. Lee, P. K. Singal, K. G. Varley, J. C. Yates: Subcellular Ca2+ transport in different areas of dog heart. Canad. J. Physiol. Pharmacol.58, 360–367 (1980).
Edman, K. A. P.: The role of non-uniform sarcomere behaviour during relaxation of striated muscle. Europ. Heart J.1 Suppl. A, 49–57 (1980).
Edman, K. A. P., G. Elzinga, M. I. M. Noble: Critical sarcomere extension required to recruit a decaying component of extra force during stretch in tetanic contractions of frog skeletal muscle fibers. J. Gen. Physiol.78, 365–382 (1981).
Edman, K. A. P., E. Nilsson: Time course of the active state in relation to muscle length and movement: a comparative study on skeletal muscle and myocardium. Cardiovasc. Res. Suppl.1, 3–10 (1971).
Edman, K. A. P., E. Nilsson: Relationships between force and velocity of shortening in rabbit papillary muscle. Acta Physiol. Scand.85, 488–500 (1972).
Flitney, F. W., D. G. Hirst: Cross bridge detachment and sarcomere “give” during strecht of active frog's muscle. J. Physiol. (London)276, 449–456 (1978).
Gibbs, C. L.: Cardiac energetics. Physiol. Rev.58, 174–254 (1978).
Huxley, A. F.: Muscle structure and theories of contraction. Progr. Biophys.7, 255–313 (1957).
Julian, F. J.: Activation in a skeletal muscle contraction model with a modification for insect fibrillar muscle. Biophys. J.9, 547–570 (1969).
Julian, F. J., M. R. Sollins: Sarcomere length-tension relations in living rat papillary muscle. Circulat. Res.37, 299–308 (1975).
Korecky, B., L. H. Michael: Regional differences in contractions of mammalian hearts. In “Recent advances in studies on cardiac structure and metabolism”. Vol. 4, edited by N. S. Dhalla, Baltimore, University Park Press, 77–87 (1974).
Kauffman, R. C., R. M. Bayer, C. Harnash: Autoregulation of contractility in the myocardial cell. Displacement as a controlling parameter. Pflügers Arch.332, 96–116 (1972).
Lecarpentier, Y. C., L. H. S. Chuck, P. R. Housmans, N. M. De Clerck, D. L. Brutsaert: Nature of the load dependence of relaxation in cardiac muscle. Amer. J. Physiol.237, H455-H460 (1979).
McNutt, N. S., D. W. Fawcett: Ultrastructure of the cat myocardium: II atrial muscle. J. Cell Biol.42, 46–57 (1969).
Nassar, R., A. Manring, E. A. Johnson: Light diffraction of cardiac muscle: sarcomere motion during contraction. In: Physiological basis of Starling's law of the heart, edited by R. Porter and D. W. Fitzsimmons, Ciba Found. Symp.,24, 57–81 (1974).
Page, E., P. I. Polimeni, R. Zak, J. Earley, M. Johonson: Myofibrillar mass in rat and rabbit heart muscle-correlation of microchemical and stereological measurements in normal and hypertrophic hearts. Circulat. Res.30, 430–439 (1972).
Poole-Wilson, P. A., I. R. Cameron: ECS, intracellular pH and electrolytes of cardiac and skeletal muscle. Amer. J. Physiol.229, 1299–1304 (1975).
Poggesi, C., L. Ricciardi, C. Reggiani, R. Minelli: Isometric relaxation in rat myocardium: load dependence and influence of caffeine. Experientia35, 1615–1616 (1979).
Roulet, M. J., K. G. Mongo, G. Vassort, R. Ventura-Clapier: The dependence of twitch relaxation on sodium ions and on internal Ca2+ stores in voltage clamped frog atrial fibres. Pflügers Arch.379, 259–268 (1979).
Stephens, N. L., V. A. Claes, D. L. Brutsert: Relaxation of tetanized canine tracheal smooth muscle. Pflügers Arch.390, 175–178 (1981).
Strobeck, J. E., A. S. Bahler, E. H. Sonneblick: Isotonic relaxation in cardiac muscle. Amer. J. Physiol.229, 646–651 (1975).
Urthaler, F., A. A. Walker, L. L. Hefner, T. N. James: Comparison of contractile performance of canine atrial and ventricular muscles. Circulat. Res.37, 762–771 (1975).
Urthaler, F., A. A. Walker, K. Kawamura, L. L. Hefner, T. N. James: Canine atrial and ventricular muscle mechanics studied as a function of age. Circulat. Res.42, 703–713 (1978).
Yazaki, Y., S. Ueda, R. Nagay, K. Shimada: Cardiac atrial myosin adenosine triphosphatase of animals and humans. Circulat. Res.45, 522–527 (1979).
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This work was partially supported by a grant of M.P.I.
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Poggesi, C., Reggiani, C., Bottinelli, R. et al. Relaxation in atrial and ventricular myocardium: activation decay and different load sensitivity. Basic Res Cardiol 78, 256–265 (1983). https://doi.org/10.1007/BF01907435
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DOI: https://doi.org/10.1007/BF01907435