Endothermic force generation in skinned cardiac muscle from rat
- K. W. Ranatunga
- … show all 1 hide
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
Isometric tension responses to rapid temperature jumps (T-jumps) of 2–6°C were examined in skinned muscle fibre bundles isolated from papillary muscles of the rat heart. T-jumps were induced by an infra-red laser pulse (wave length 1.32 μm, pulse duration 0.2 ms) obtained from a Nd-YAG laser, which heated the fibres and bathing buffer solution in a 50 μl trough; the increased temperature by laser pulse was clamped at the high temperature by a Peltier system (see Ranatunga, 1996). In maximally Ca2+-activated (pCa ca. 4.5) fibres, the relationship between tension and temperature was non-linear, the increase of active tension with temperature being more pronounced at lower temperatures (below ca. 20°C). A T-jump at any temperature (range 3–35°C) induced an initial step decrease of tension of variable amplitude (Phase 1), probably due to thermal expansion, and it was followed by a tension transient which resulted in a net rise of tension above the pre-T-jump level. The rate of net rise of tension (Phase 2b or endothermic force generation) was 7–10/s at ca. 12°C and its Q10 was 6.3 (below 25°C). In cases where the step decrease of tension in Phase 1 was prominent, an initial quick tension recovery phase (Phase 2a, 70–100/s at 12°C) that did not contribute to a rise of tension above the pre-T-jump level, was also seen. This phase (Phase 2a) appeared to be similar to the quick tension recovery induced by a small length release and its rate increased with temperature with a Q10 of 1.8. In some cases where Phase 2a was present, a slower tension rise (Phase 3) was seen; its rate (ca. 5/s) was temperature-insensitive. The results show that the rate of endothermic force generation in cardiac fibres is clearly different from that of either fast-twitch or slow-twitch mammalian skeletal muscle fibres; implication of such fibre type-specific differences is discussed in relation to the difficulty in identifying the biochemical step underlying endothermic cross-bridge force generation.
- Bershitsky SY and Tsaturyan AK (1989) Effect of joule temperature jump on tension and stiffness of skinned rabbit muscle fibers. Biophys J 56: 809–816.
- Bershitsky SY and Tsaturyan AK (1992) Tension responses to joule temperature jump in skinned rabbit muscle fibers. J Physiol 447: 425–448.
- Bershitsky SY, Tsaturyan AK, Bershitskaya ON, Mashanov GI, Brown P, Burns R and Ferenczi MA (1997) Muscle force is generated by myosin heads stereospecifically attached to action. Nature 388: 186–190.
- Dantzig JA, Goldman YE, Millar NC, Lacktis J and Homsher E (1992) Reversal of the crossbridge force-generating transition by photogeneration of phosphate in rabbit psoas muscle fibres. J Physiol 451: 247–275.
- Davis JS and Harrington WF (1987) Force generation by muscle fibers in rigor: a laser temperature-jump study. Proc Natl Acad Sci USA 84: 975–979.
- Davis JS and Harrington WF (1993) A single order-disorder transition generates tension during the Huxley-Simmons phase-2 in muscle. Biophys J 65: 1886–1898.
- Davis JS and Rodgers ME (1995a) Force generation and temperature-jump and length-jump tension transients in muscle fibers. Biophys J 68: 2032–2040.
- Davis JS and Rodgers ME (1995b) Indirect coupling of phosphate release to de-novo tension generation during muscle contraction. Proc Natl Acad Sci USA 92: 10482–10486.
- De Tombe PP and ter Keurs HEDJ (1990) Force and velocity of sarcomere shortening in trabeculae from rat heart. Circul Res 66: 1239–1254.
- Ford LE, Huxley AF and Simmons RM (1977) Tension responses to sudden length change in stimulated frog muscle fibres near slack length. J Physiol 269: 441–515.
- Fortune NS, Geeves MA and Ranatunga KW (1989) Pressure sensitiv-ity of active tension in glycerinated rabbit psoas muscle fibres: effect of ADP and phosphate. J Muscle Res Cell Motil 10: 113–123.
- Fortune NS, Geeves MA and Ranatunga KW (1991) Tension responses to rapid pressure release in glycerinated rabbit muscle fibers. Proc Natl Acad Sci USA 88: 7323–7327.
- Goldman YE, McCray JA and Ranatunga KW (1987) Transient tension changes initiated by laser temperature jumps in rabbit muscle fibres. J Physiol 392: 71–95.
- Harrison SM and Bers DM (1990) Modification of temperature dependence of myofilament Ca sensitivity by troponin C replace-ment. Am J Physiol 258: C282–C288.
- Huxley AF and Simmons RM (1971) Proposed mechanism of force generation in striated muscle. Nature 233: 533–538.
- Irving M, Lombardi V, Piazzesi G and Ferenczi MA (1992) Myosin head movements are synchronous with the elementary force-generating process in muscle. Nature 357: 156–158.
- Irving M, Allen T St C, Sabido-David C, Craik JS, Brandmeirer B, Kendrick-Jones J, Corrie JET, Trentham DR and Goldman YE (1995) Tilting of the light-chain region of myosin during step length changes and active force generation in skeletal muscle. Nature 375: 688–691.
- Millar NC and Holmsher E (1992) Kinetics of force generation and phosphate release in skinned rabbit soleus muscle fibers. Am J Physiol 262: C1239–C1245.
- Ranatunga KW (1984) The force-velocity relation of rat fast-and slow-twitch muscles examined at different temperatures. J Physiol 351: 517–529.
- Ranatunga KW (1994) Thermal stress and Ca-independent contractile activation in mammalian skeletal muscle fibers at high tempera-tures. Biophys J 66: 1531–1541.
- Ranatunga KW (1996) Endothermic force generation in fast and slow mammalian (rabbit) muscle fibers. Biophys J 71: 1905–1913.
- Ranatunga KW (1997) Laser temperature jump experiments on mammalian (rat) cardiac muscle fibers. J Physiol 504.P: 62P.
- Wang G and Kawai M (1997) Force generation and phosphate release steps in skinned rabbit soleus slow-twitch muscle fibers. Biophys J 73: 878–894.
- Zhao Y and Kawai M (1994) Kinetic and thermodynamic studies of the cross-bridge cycle in rabbit psoas muscle fibers. Biophys J 67: 1655–1688.
- Endothermic force generation in skinned cardiac muscle from rat
Journal of Muscle Research & Cell Motility
Volume 20, Issue 5-6 , pp 489-496
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers
- Additional Links
- K. W. Ranatunga (1)
- Author Affiliations
- 1. Department of Physiology, School of Medical Sciences, University of Bristol, Bristol, BS8 ITD, UK