Pflügers Archiv

, Volume 394, Issue 4, pp 338–346 | Cite as

Factors modulating the sensitivity of the relaxation to the loading conditions in rat cardiac muscle

  • C. Poggesi
  • C. Reggiani
  • L. Ricciardi
  • R. Minelli
Excitable Tissues and Central Nervous Physiology


The load sensitivity of the relaxation phase was studied in rat papillary muscle, with isotonic afterloaded contractions and stretches applied after the peak of isometric twitches.

The tension decay occurred earlier in isotonic than in isometric contractions. When a central region of the preparation was marked with small stainless steel pins, a lengthening of this region could be shown during relaxation of isometric (fixed end) contractions. This lengthening was earlier and faster in isotonic afterloaded contractions. Therefore the sensitivity of relaxation to load or length changes could be described in the context of the general mechanism of relaxation which takes into account the non uniform behaviour of the muscle and the internal movement during contractions.

Interventions which decelerate the activation decay rate had different effects on the load dependence of relaxation. Caffeine addition and substitution of strontium for calcium abolished the load sensitivity while a temperature reduction had no influence on it.

Key words

Cardiac muscle Relaxation phase Load sensitivity 


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  1. Abbott BC, Mommaerts WFHM (1959) A study of inotropic mechanisms in the papillary muscle preparation. J Gen Physiol 42:533–551Google Scholar
  2. Bahler AS (1971) Mechanical properties of relaxing frog skeletal muscle. Am J Physiol 220:1983–1990Google Scholar
  3. Barany M (1967) ATPase activity of myosin correlated with speed of muscle shortening. J Gen Physiol 50:197–216Google Scholar
  4. Bass BG, Ciulla EM, Klop P, van Baal S (1975) Some electrical and mechanical effects of strontium on toad ventricular muscle: comparison to calcium. J Physiol (Lond) 252:547–564Google Scholar
  5. Blayney L, Thomas H, Muir J, Henderson A (1978) Action of caffeine on calcium transport by isolated fractions of myofibrils, mitochondria and sarcoplasmic reticulum of rabbit heart. Circ Res 43:520–526Google Scholar
  6. Blinks JR, Olson CB, Jewell BR, Braveny P (1972) Influence of caffeine and other methylxanthines on mechanical properties of isolated mammalian heart muscle. Circ Res 30:367–392Google Scholar
  7. Bodem R, Sonnenblick EH (1975) Mechanical activity of mammalian heart muscle: variable onset, species differences and the effect of caffeine. Am J Physiol 228:250–261Google Scholar
  8. Brady AJ (1966) Onset of contractility in cardiac muscle. J Physiol (Lond) 184:560–580Google Scholar
  9. Brutsaert DL, De Clerck NM, Goethals MA, Housmans PR (1978) Relaxation of ventricular cardiac muscle. J. Physiol (Lond) 282:469–480Google Scholar
  10. Brutsaert DL, Housmans PR, Goethals MA (1980) Dual control of relaxation: its role in the ventricular function in the mammalian heart. Circ Res 47:637–652Google Scholar
  11. Donald TC, Reeves DNS, Reeves RC, Walker AA, Hefner LL (1980) Effect of damaged ends in papillary muscle preparations. Am J Physiol 238:H14-H23Google Scholar
  12. Edman KAP (1980) The role of non-uniform sarcomere behaviour during relaxation of striated muscle. Eur Heart J 1 Suppl A:49–57Google Scholar
  13. Edman KAP, Elzinga G, Noble MIM (1981) Critical sarcomere extension sequired to recruit a decaying component of extra force during stretch in tetanic contractions of frog skeletal muscle fibers. J Gen Physiol 78:365–382Google Scholar
  14. Edman KAP, Nilsson E (1968) The mechanical parameters of myocardial contraction studied at a constant length of the contractile element. Acta Physiol Scand 72:205–219Google Scholar
  15. Edman KAP, Nilsson E (1971) Time course of the active state in relation to muscle length and movement: a comparative study on skeletal muscle and myocardium. Cardiovasc Res Suppl 1:3–10Google Scholar
  16. Edman KAP, Nilsson E (1972) Relationships between force and velocity of shortening in rabbit papillary muscle. Acta Physiol Scand 85:488–500Google Scholar
  17. Eisenberg E, Hill TL, Chen Y (1980) Cross bridge model of muscle contraction. Quantitative analysis. Biophys J 29:195–227Google Scholar
  18. Fabiato A, Fabiato F (1977) Calcium release from the sarcoplasmic reticulum. Circ Res 40:119–129Google Scholar
  19. Flitney FW, Hirst DG (1978) Cross bridge detachment and sarcomere “give” during stretch of active frog's muscle. J Physiol (Lond) 276:449–456Google Scholar
  20. Gibbs CL (1978) Cardiac energetics. Physiol Rev 58:174–254Google Scholar
  21. Harigaya S, Schwartz A (1969) Rate of calcium binding and uptake in normal animal and failing human cardiac muscle. Membrane vesicles (relaxing factor) and mitochondria. Circ. Res. 25:781–794Google Scholar
  22. Henderson AH, Brutsaert DL, Forman R, Sonnenblick EH (1974) Influence of caffeine on force development and force frequency relations in cat and rat heart muscle. Cardiovasc Res 8:162–172Google Scholar
  23. Henderson AH, Cattell MR (1976) Prolonged biphasic strontium mediated contractions of cat and frog heart muscle and their responses to inotropic influences. J Mol Cell Cardiol 8:299–319Google Scholar
  24. Huntsman LL, Joseph DS, Oiye MY, Nichols GL (1979) Auxotonic contractions in cardiac muscle segments Am J Physiol 237:H131-H138Google Scholar
  25. Jewell BR, Wilkie DR (1960) The mechanical properties of relaxing muscle. J Physiol (Lond) 152:30–47Google Scholar
  26. Jewell BR, Rovell JM (1973) Influence of previous mechanical events on the contractility of cat papillary muscle. J Physiol (Lond) 235:710–740Google Scholar
  27. Johansson B, Hellstrand P (1975) Isometric and isotonic relaxation in venous smooth muscle. Acta Physiol Scand 93:167–174Google Scholar
  28. Julian FJ, Sollins MR (1975) Sarcomere length-tension relations in living rat papillary muscle. Circ Res 37:299–308Google Scholar
  29. Julian FJ, Sollins MR, Moss RL (1976) Absence of a plateau in length tension relationship of a rabbit papillary muscle when internal shortening is prevented. Nature 260:340–342Google Scholar
  30. Kauffman RC, Bayer RM, Harnash C (1972) Autoregulation of contractility in the myocardial cell. Displacement as a controlling parameter. Pflügers Arch 332:96–116Google Scholar
  31. Krueger JW, Pollack GH (1975) Myocardial sarcomere dynamics during isometric contractions. J Physiol (Lond) 251:627–643Google Scholar
  32. Lecarpentier YC, Chuck LHS, Housmans PR, de Clerck NM, Brutsaert DL (1979) Nature of the load dependence of relaxation in cardiac muscle. Am J Physiol 237:H455-H460Google Scholar
  33. Mattiazzi AR, Nilsson E (1976) The influence of temperature on the time course of the mechanical activity in rabbit papillary muscle. Acta Physiol Scand 97:310–318Google Scholar
  34. Poggesi C, Ricciardi L, Reggiani C, Minelli R (1979) Isometric relaxation in rat myocardium: load dependence and influence of caffeine. Experientia 35:1615–1616Google Scholar
  35. Reggiani C, Poggesi C, Ricciardi L, Minelli R (1980) Time course and duration of the depressant effect of active shortening in cardiac muscle. Pflügers Arch 385:273–276Google Scholar
  36. Saeki Y, Sagawa K, Suga H (1980) Transient tension responses of heart muscle in Ba contracture to step length changes. Am J Physiol 238:H340-H347Google Scholar
  37. Stephens NL, Claes VA, Brutsaert DL (1973) Relaxation of tetanized canine tracheal smooth muscle. Pflügers Arch 390:175–178Google Scholar
  38. Strauer BE (1973) Force-velocity relations of isotonic relaxation in mammalian heart muscle. Am J Physiol 224:431–434Google Scholar
  39. Strobeck JE, Bahler AS, Sonnenblick EH (1975) Isotonic relaxation in cardiac muscle. Am J Physiol 229:646–651Google Scholar
  40. Ter Keurs HEDJ, Rijnsburger WH, Van Heuningen R, Nagelsmit MJ (1980) Tension development and sarcomere length in rat cardiac trabeculae. Circ Res 46:703–714Google Scholar
  41. Wiegner AW, Bing OHL (1977) Altered performance of rat cardiac muscle follows changes in mechanical stress during relaxation. Circ Res 41:691–693Google Scholar

Copyright information

© Springer-Verlag 1982

Authors and Affiliations

  • C. Poggesi
    • 1
  • C. Reggiani
    • 1
  • L. Ricciardi
    • 1
  • R. Minelli
    • 1
  1. 1.Istituto di Fisiologia UmanaUniversità di PaviaPaviaItaly

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