A note on the heat of activation in a muscle twitch

1950 ◽  
Vol 137 (888) ◽  
pp. 330-331 ◽  
Keyword(s):  
Heat Production ◽  
Mechanical Work ◽  
Muscle Twitch ◽  
Extreme Loads

Under extreme loads a stimulated muscle neither shortens nor develops tension. The heat production in a twitch is then rather less than one-half of its value with maximal shortening. Under such conditions the heat of shortening and the mechanical work are nil. The remaining heat, therefore, is heat of activation alone. It is about the same in magnitude and onset as the heat of activation at ordinary lengths.

The priority of the heat production in a muscle twitch

1958 ◽  
Vol 148 (932) ◽  
pp. 397-402 ◽  
Keyword(s):  
Chemical Reactions ◽  
Heat Production ◽  
Mechanical Response ◽  
Substantial Part ◽  
Hypertonic Solution ◽  
Isotonic Solution ◽  
Muscle Twitch ◽  
Previous Conclusion

When a muscle has been soaked in a moderately hypertonic solution its mechanical response to a shock is delayed, but its heat production is almost normal and starts considerably earlier than its shortening. After a more hypertonic solution the mechanical response is abolished, but a substantial part of the heat production remains. These effects are rapidly reversed by soaking in a normal isotonic solution. They strengthen the previous conclusion that chemical reactions triggered by a stimulus precede the mechanical response.

Body Temperature and Singing in the Bladder Cicada, Cystosoma Saundersii

1979 ◽  
Vol 80 (1) ◽  
pp. 69-81 ◽  
Author(s):  
R. K. JOSEPHSON ◽  
D. YOUNG
Keyword(s):  
Heat Production ◽  
Cell Biology ◽  
Sound Production ◽  
Marked Decrease ◽  
Cooling Curve ◽  
Muscle Twitch ◽  
Temperature Excess ◽  
Air Mixing ◽  
Artificial Heat ◽  
Sound Pulses

1. Body temperatures during singing were measured in the cicada, Cystosoma saundersii Westwood, both in the field and in tethered animals indoors. 2. The temperature of the sound-producing tymbal muscle rises rapidly during singing to reach a plateau approximately 12°C above ambient. This produces a temperature gradient in the abdominal air sac which surrounds the muscle. When singing stops, the tymbal muscle cools exponentially. 3. Heat production during singing, estimated from the cooling curve, is 4.82 cal min−1 g muscle−1. Generation of the same temperature excess in the air sac by an artificial heat source yields an estimated heat production of 54.4 cal min−1 g muscle−1. This discrepancy may be caused by air mixing in the air sac during singing. 4. As temperature rises, tymbal muscle twitch contractions become faster and stronger. This and heat transfer to the thorax cause changes in the song pattern: a marked decrease in the interval between the two sound pulses produced by a single tymbal buckling and a lesser decrease in the interval between bucklings. The fundamental sound period remains unaltered. These effects are consistent with earlier data on sound production. Note: Present address: Department of Developmental and Cell Biology, University of California, Irvine, California 92717, U.S.A.

The positive and negative heat production associated with a nerve impulse

1958 ◽  
Vol 148 (931) ◽  
pp. 149-187 ◽  
Keyword(s):  
Chemical Reactions ◽  
Heat Production ◽  
Surface Membrane ◽  
Nerve Impulse ◽  
Active Phase ◽  
Fibre Surface ◽  
Excitable Membrane ◽  
Substantial Part ◽  
Recording Equipment ◽  
Muscle Twitch

The ‘initial’ heat production of a non-medullated nerve ( Maia ) has been reinvestigated with more rapid recording equipment than was previously available. In a single impulse at 0° C a positive heat production was observed averaging about 9 x 10 -6 cal/g nerve: this is rapid and is probably associated with the active phase of the impulse. It is followed by a rather slower heat absorption averaging about 7 x 10 -6 cal/g nerve and lasting for about 300 ms. Previous methods were too slow to do more than record the difference between the two, the ‘net heat’, viz. about 2 x 10 -6 cal/g nerve: this is about one-third greater at 0°C than at 18° C. Maia nerves contain fibres from 20 to 0.3 µ in diameter, and about half the heat is probably derived from fibres less than 3.0 µ . The velocities of impulses in them at 0° C vary from 1.4 to 0.1 m/s, so impulses reach the recording thermojunctions throughout a long interval. Thus the observed course of the heat production is the resultant of positive and negative components in different fibres, and a substantial part of each is masked. The real positive and negative heats, therefore, are substantially greater than those observed: on the most likely estimate of velocity distribution, in a single impulse at 0° C they are about 14 x 10 -6 cal/g and — 12 x 10 -6 cal/g, respectively. Heat production, like ionic interchange, is probably proportional to fibre surface, which in 1 g of Maia nerve is estimated as 10 4 cm 2 . If the fibre surface is taken as 50 Å thick, the heats just calculated, if reckoned per gram of surface material, are 2.8 x 10 -3 cal and — 2.4 x 10 -3 cal, respectively. The former is about the same as the heat produced per gram in a muscle twitch. During the passage of an impulse there is known to be an interchange of Na and K ions between the axoplasm and the outside fluid. When isotonic solutions of NaCl and KCl are mixed there is a production of heat. A substantial part of the heat during an impulse may be derived from the interchange of Na and K. Another part may be associated with chemical reactions occurring in the excitable membrane during the cycle of permeability change accompanying the passage of an impulse. The negative heat production is discussed. It cannot be connected with ‘pumping back’ the Na and K ions; this is a much slower process and anyhow would probably involve a positive heat production. It may be a sign of endothermic chemical reactions, representing a first (anaerobic) stage in recovery, which occur in the surface membrane following the completion of the permeability cycle. The question is considered whether the positive and negative phases of the heat production could be due to the discharge and recharge, during the action potential, of the condenser residing in the excitable membrane. The heats so calculated are of the right order of size, but on present evidence the time relations seem to be quite wrong. The amount of K which escapes per impulse from Maia nerve during slow repetitive stimulation at 0° C was measured. It depends greatly on frequency of stimulation; at ‘zero frequency’ it was about 9 X 10 -8 mole/g x impulse.

scholarly journals The absolute value of the isometric heat coefficient TI/H in a muscle twitch, and the effect of stimulation and fatigue

1928 ◽  
Vol 103 (723) ◽  
pp. 163-170 ◽  
Keyword(s):  
Lactic Acid ◽  
Heat Production ◽  
Muscle Length ◽  
Mean Value ◽  
Sartorius Muscle ◽  
Muscle Twitch ◽  
Absolute Value ◽  
The Subject ◽  
The Absolute ◽  
Initial Heat

It is not technically possible to determine directly the lactic acid set free in a sing1e muscle twitch. It is necessary to calculate it from the initial heat production, or from the tension developed. The anaerobic liberation of 1 gramme of lactic acid in musc1e is accompanied, according to Meyerhof, by the production of 385 calories of heat (1). This 1eads to the equation:- 1 gramme-cm.(heat) ≡ 6·14 × 10 -8 gramme lactic acid. (I) The isometric coefficient of lactic acid, defined for a twitch or a series of twitches by the equation* K m =(grammes tension developed) (cms. muscle length)/(grammes lactic acid produced), has been the subject of much investigations by meyerhof and his colleagues (2, 3, 4, 5). Matsuoka, for the frog's sartorius muscle in Ringer's solutions, found a mean value of 1·05 × 10 8 (variation 0·69 to 1·36). Meyerhof and Lohmann, for frog's gastrocnemius, gave 1·40 × 10 8 as a mean, while Meyerhof and Suchulz gave 1·43 × 10 8 (variation 1·12 to 1·66). In the gastrocnemius, however, the fibres are not straight, and do not run parallel to the muscle length; consequently it is necessary to mutiply (see Mashino(6), A. V. Hill(7)) the value so found by a factor of roughly 0·63 to allow for the skew disposition of the fibres. This gives, when corrected, 0·9 × 10 8 for the gastrocnemius, so that taking account of the value 1·05 × 10 8 found by Matsuoka for the sartorius, the round figure 1 × 10 8 may be accepted. This leads to the equation:- 1 gramme-cm.(tension-length) ≡ 10 -8 gramme lactic acid.

scholarly journals The onset of contraction

1949 ◽  
Vol 136 (883) ◽  
pp. 242-254 ◽  
Keyword(s):  
Heat Production ◽  
Maximum Rate ◽  
Direct Evidence ◽  
Mechanical Response ◽  
Muscle Twitch ◽  
Chemical Methods ◽  
Physical Methods ◽  
Critical Comparison ◽  
Sequence Of Events ◽  
Activation Heat

The early heat production during the onset of a muscle twitch has been determined with the greatest precision possible for comparison with the mechanical response. When allowance is made for the time taken in propagation the heat is found to start off at its maximum rate. Its rate falls gradually to a constant value, while the muscle continues to shorten uniformly then decreases to zero as shortening draws to an end. The heat occurs in two separate processes, those of activation and shortening respectively. The heat of activation has well started before shortening is detected by ordinary methods. The heat of shortening runs parallel to the shortening. There is no sign of negative heat production at any stage of contraction. If endothermic processes occur they are exactly masked by exothermic ones. The latent period of the activation heat is about 10 msec. at 0°C in frog’s muscle, about 25 msec. in toad’s muscle. These, with an ordinary value of Q10, would correspond at 20°C to about 2 and 5 msec. respectively. Various physical methods are discussed of examining the rapid processes that occur during contraction. Chemical methods are inadequate in speed and sensitivity to give direct evidence of the nature and sequence of events occurring in a twitch. Theoretical con­clusions from experiments on muscle extracts, without critical comparison with the behaviour of living muscle, may lead to confusing results.

scholarly journals Man's mechanical efficiency in work performance and the cost of the movements involved (treated separately)

1917 ◽  
Vol 89 (618) ◽  
pp. 394-410
Keyword(s):  
Heat Production ◽  
Work Performance ◽  
Original Data ◽  
Mechanical Efficiency ◽  
The Body ◽  
Mechanical Work ◽  
Published Data ◽  
Total Data ◽  
The Subject ◽  
Group B

Many of the data contained in this paper have been already published and submitted to a preliminary process of analysis. From the arrangement then made it was seen that the body-weight exercised two separate, and opposing, influences on the heat production associated with muscular work. A certain steady rate of movement was maintained throughout a long series of experiments, and this was complicated to a different degree, in different groups of experiments, with the performance of different, increasing, amounts of mechanical work. When the heat production was comparatively small, in the case of minimal work performance, it was observed to vary directly with the body-weights of the individual subjects. On the other hand, when larger, this variation was less noticeable, and at a certain stage of increase in the performance of work it was found to have disappeared completely. The fact was very definite, so that in four different groups of experiments arranged in order of reference to rising values of mechanical work the total heat productions measured varied in Group A directly with W 4/3 , in Group B with W ⅔ , in Group C with W ⅓ , and in Group D with W 0 ( loc cit ., p. 111). No attempt was made at the time, other than contained in a statement of suggestions requiring consideration, to explain this phenomenon, for which course, indeed, an excuse might be found in the labour involved in collecting the information, and the even greater labour of dealing similarly with the very extensive series of measurements underlying the published data. To this problem, then, attention is once more directed in the present paper. In the meantime, these original data have been elaborately and excellently examined by Glazebrook and Dye in a manner meriting very considerable interest. Before once more encountering these facts, an explanation of the chief terms utilised may be of advantage, since the mode of experiment and the actual measurements have of necessity to be kept out of sight, and no opportunities arise therefore for an observation of the way in which the measurements are summed to form the total data displayed. Thus, for example, the main data, throughout termed “heat productions,” include frequently a larger quantity of heat than that dissipated from the experi­mental subject as such, since they include an allowance made for any additional heat stored in his body (an allowance assessed with reference to the rectal temperature), and also include the heat dissipated from the experi­mental machine (cycle) whenever, and to the same extent as, work is performed upon it by the subject. It is clear that only such sums of the total transformation of energy by the subject are of major physiological interest, as alone equivalent to data obtained from examinations of the exchange of oxygen and carbon dioxide in the concomitant process of respiration, and to data obtained in any other fashion as to the oxidation of material in the body.

scholarly journals On the heat production associated with muscular work

1914 ◽  
Vol 87 (595) ◽  
pp. 311-317 ◽  
Keyword(s):  
Heat Production ◽  
Simple Formula ◽  
Mechanical Work ◽  
Muscular Work ◽  
Measured Amount ◽  
Straight Line ◽  
Number Of Individuals

On reading Prof. Macdonald’s paper it appeared that it might be interesting to see if his results connecting the heat production and muscular work could be expressed graphically or by means of some simple formula. The tables in his paper give the heat production in calories per hour of a number of individuals when doing a carefully measured amount of mechanical work on a kind of treadmill or cycle. This amount of work is kept constant for each group of observations in the paper. On plotting these as is done in fig. 1, it is clear that the points lie very approximately on a straight line, and it is easily seen that the equation to this line, may be written H = 128 + W/0·256;

A reinvestigation of two critical points in the energetics of muscular contraction

1953 ◽  
Vol 141 (905) ◽  
pp. 503-510 ◽  
Keyword(s):  
Heat Production ◽  
Critical Points ◽  
Major Part ◽  
Contractile Activity ◽  
Muscular Contraction ◽  
Active State ◽  
Mechanical Work ◽  
Extra Energy ◽  
Energy Exchanges

Two critical points in the energetics of muscular contraction have been re-examined: (1) the absence of heat production after the active state has ended (i. e. in ‘relaxation’) and (2) the mobilization of extra energy for the performance of work. So long as contractile activity persists heat is produced and work can be done; relaxation is merely the disappearance or cessation of that activity. When mechanical work is performed extra energy is called for, which is equal to or slightly exceeds the work. The heat of shortening and the extra energy for work are not trivial, but make up the major part of the energy exchanges of contraction.

Muscle–twitch Correlates of Piagetian Cognitions

1975 ◽  
Vol 20 (5) ◽  
pp. 426-427
Author(s):  
DAVID ZEAMAN
Keyword(s):  
Muscle Twitch
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