Heat changes during transient tension responses to small releases in active frog muscle

Gilbert, Susan H.; Ford, Lincoln E.

doi:10.1016/s0006-3495(88)82996-5

Cited by 20 publications

(19 citation statements)

References 16 publications

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“…Gilbert & Ford (1988) measured the heat change during the fast increase in force from T 1 to T 2 that follows a length step. The experiments were done with whole sartorius muscle from frog.…”

Section: Calorimetry Gives a Paradoxical Resultsmentioning

confidence: 99%

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Temperature change as a probe of muscle crossbridge kinetics: a review and discussion

2009

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Following the ideas introduced by Huxley (Huxley 1957, Prog. Biophys. Biophys. Chem. 7, 255-318), it is generally supposed that muscle contraction is produced by temporary links, called crossbridges, between myosin and actin filaments, which form and break in a cyclic process driven by ATP splitting. Here we consider the interaction of the energy in the crossbridge, in its various states, and the force exerted. We discuss experiments in which the mechanical state of the crossbridge is changed by imposed movement and the energetic consequence observed as heat output and the converse experiments in which the energy content is changed by altering temperature and the mechanical consequences are observed. The thermodynamic relationship between the experiments is explained and, at the first sight, the relationship between the results of these two types of experiment appears paradoxical. However, we describe here how both of them can be explained by a model in which mechanical and energetic changes in the crossbridges occur in separate steps in a branching cycle.

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Section: Calorimetry Gives a Paradoxical Resultsmentioning

confidence: 99%

“…(b) Heat change during the rapid tension recovery after a quick release. Open circles, observations of Gilbert & Ford (1988). It has been assumed here that 35% of the bridges were attached and the heat change per attached bridge is plotted.…”

Section: Calorimetry Gives a Paradoxical Resultsmentioning

confidence: 99%

Temperature change as a probe of muscle crossbridge kinetics: a review and discussion

2009

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“…constant K = kN F/kFN at 20°C which cannot be determined accurately enough. It should be noted that heat measurements in frog muscle after step shortening (Gilbert & Ford, 1988) also showed a positive enthalpy change associated with a rapid forcegeneration step.…”

Section: Kinetic Modelmentioning

confidence: 99%

Tension responses to joule temperature jump in skinned rabbit muscle fibres.

Bershitsky¹,

Tsaturyan²

1992

The Journal of Physiology

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SUMMARY1. Joule temperature jumps (T-jumps) from 5-9°C up to 40°C were used to study the cross-bridge kinetics and thermodynamics in skinned rabbit muscle fibres. To produce a T-jump, an alternating current pulse was passed through a fibre 5 s after removing the activating solution (pCa -4-5) from the experimental trough. The pulse frequency was -30 kHz, amplitude < 3 kV, and duration 0-2 ms. The pulse energy liberated in the fibre was calculated using a special analog circuit and then used for estimation of the T-jump amplitude.2. The T-jump induced a tri-exponential tension transient. Phases 1 and 2 had rate constants k1 = 450-1750 s-1 and k2 = 60-250 s-1 respectively, characterizing the tension rise, whereas phase 3 had a rate constant k3 = 5-10 s-5 representing tension recovery due to the fibre cooling.3. An increase from 13 to 40°C for the final temperature achieved by the T-jump led to an increase in the amplitudes of phases 1 and 2. After T-jumps to 30-40°C during phase 1, tension increased by 50-80 %. During phase 2 an approximately 2-fold tension increase continued. Rate constants k. and k2 increased with temperature and temperature coefficients (Q1o) were 1P6 and 1-7, respectively. 4. To study which processes in the cross-bridges are involved in phases 1 and 2, a series of experiments were made where step length changes of -9 to +3 nm (hs)-1(nanometres per half-sarcomere length) were applied to the fibre 4 ms before the T-jump.5. After the step shortening, the rate constant of phase 1 increased, whereas its amplitude decreased compared to those without a length change. This indicates that phase 1 is determined by some force-generating process in the cross-bridges attached to the thin filaments. This process is, most probably, the same as that producing the early tension recovery following the length change. The enthalpy change (AH) associated with the reaction controlling this process was estimated to be positive (15-30 kJ mol').

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“…26) to obtain an accurate representation of the time response over the entire interval of interest. The step response of one of the thermopiles used by Gilbert and Ford (1988) is shown by solid lines. The symbols show step responses obtained by replacing its mylar insulation with a material having the same Vas mylar but a k value twice as high (diamonds) or with another material having the same k but a V value twice as high (triangles).…”

Section: Effects Of Diffusivity and Thermal Capacitymentioning

confidence: 99%

“…Step responses of the two thermopiles used in the study described in the accompanying paper (Gilbert and Ford, 1988) are shown in Fig. 4.…”

Section: Responses Of Modern Thermopilesmentioning

confidence: 99%

Analysis of diffusion delay in a layered medium. Application to heat measurements from muscle

Gilbert

Mathias

1988

Biophysical Journal

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An analysis is presented of diffusional delays in one-dimensional heat flow through a medium consisting of several layers of different materials. The model specifically addresses the measurement of heat production by muscle, but diffusion of solute or conduction of charge through a layered medium will obey the same equations. The model consists of a semi-infinite medium, the muscle, in which heat production is spacially uniform but time varying. The heat diffuses through layers of solution and insulation to the center of the thermal element where heat flow is zero. Using Laplace transforms, transfer functions are derived for the temperature change in the center of the thermopile as a function of the temperature at any interface between differing materials or as a function of heat production in the muscle. From these transfer functions, approximate analytical expressions are derived for the time constants which scale the early and late changes in the central temperature. We find that the earliest temperature changes are limited by the diffusivities of the materials, whereas the approach to steady state depends on the total heat capacity of the system and the diffusivity of muscle. Hill (1937) analyzed a similar geometry by modeling the layered medium as a homogeneous system with an equivalent half thickness. We show that his analysis was accurate for the materials in his system. In general, however, and specifically with regard to modern thermopiles, a homogeneous approximation will lead to significant errors. We compare responses of different thermopiles to establish the limits of time resolution in muscle heat records and to correct them for diffusional delays. Using numerical techniques, we invert the Laplace transforms and show the time course of the temperature changes recorded by different instruments in response to different patterns of heat production.

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Heat changes during transient tension responses to small releases in active frog muscle

Cited by 20 publications

References 16 publications

Temperature change as a probe of muscle crossbridge kinetics: a review and discussion

Temperature change as a probe of muscle crossbridge kinetics: a review and discussion

Tension responses to joule temperature jump in skinned rabbit muscle fibres.

Analysis of diffusion delay in a layered medium. Application to heat measurements from muscle

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