scholarly journals Energy liberation and chemical change in frog skeletal muscle during single isometric tetanic contractions.

1975 ◽  
Vol 65 (1) ◽  
pp. 1-21 ◽  
Author(s):  
E Homsher ◽  
J A Rall ◽  
A Wallner ◽  
N V Ricchiuti
Keyword(s):  
Time Course ◽  
Rana Pipiens ◽  
Rana Temporaria ◽  
Chemical Change ◽  
Systematic Difference ◽  
Energy Liberation ◽  
Designed Experiments ◽  
Proportionality Constant ◽  
Immersion Technique ◽  
Atp Breakdown

Recent data obtained from Rana temporaria sartorius muscles during an isometric tetanus indicate that the time-course of phosphocreatine (PC) splitting cannot account for the total energy (heat + work) liberation (Gilbert et al. 1971. J. Physiol. (Lond.) 218:)63). As this conclusion is important to an understanding of the chemical energetics of contraction, similar experments were performed on unpoisoned, oxygenated Rana pipiens sartorius muscles. The muscles were tetanized (isometrically) at 0 degrees C for 0.6, 1, or 5 s; metabolism was rapidly arrested by freezing the muscles with a specially designed hammer apparatus, and the frozen muscles were chemically analyzed. Comparable myothermal measurments were made on frogs from the same batch. Results of these experiments indicate: (a) The energy liberation parallels the PC and ATP breakdown with a proportionality constant of 10.7 kcal/mol; (b) comparably designed experiments with sartorius muscles of R. temporaria revealed that the ratio of energy liberation to PC splitting was significantly greater than that observed in R. pipiens sartorius muscles; (c) there is no systematic difference between experiments in which metabolism was arrested by the hammer apparatus and others using a conventional immersion technique.

scholarly journals A temporal dissociation of energy liberation and high energy phosphate splitting during shortening in frog skeletal muscles.

1976 ◽  
Vol 68 (1) ◽  
pp. 13-27 ◽  
Author(s):  
J A Rall ◽  
E Homsher ◽  
A Wallner ◽  
W F Mommaerts
Keyword(s):  
Stimulus Pattern ◽  
Skeletal Muscles ◽  
Energy Production ◽  
Time Course ◽  
Rana Pipiens ◽  
High Energy ◽  
Energy Liberation ◽  
High Energy Phosphate ◽  
Contracting Muscle ◽  
Mechanical Measurements

Measurements of the time course of high energy phosphate splitting and energy liberation were performed on rapidly shortening Rana pipiens skeletal muscles. In muscles contracting 30 times against small loads (less the 0.02P), the ratio of explained heat + work (H + W) (calculated from the measured high energy phosphate splitting) to observed H + W (from myothermal and mechanical measurements) was 0.68 +/- 0.08 and is in agreement with results obtained in isometric tetani of R. pipiens skeletal muscle. In lightly afterloaded muscles which were tetanized for 0.6a and whose metabolism was arrested at 3.0 s after the beginning of stimulation, a similar ratio of explained H + W to observed H + W was obtained. However, in identical contractions in which metabolism was arrested at 0.5-0.75 s after the beginning of stimulation, the ratio of explained H + W to observed H + W declined significantly to values ranging from 0.15 to 0.40. These results suggest that rapid shortening at the beginning of contraction induces a delay between energy production and measurable high energy phosphate splitting. This interpretation was tested and confirmed in experiments in which one muscle of a pair contracted isometrically while the other contracted against a small afterload. The afterload and stimulus pattern were arranged so that at the time metabolism was arrested, 0.5 s after the beginning of stimulation, the total energy production by both muscles was the same. Chemical analysis revealed that the isotonically contracting muscle spilt only 25% as much high energy phosphate as did the isometrically contracting muscle.

Cell volume and metabolic dependence of NEM-activated K+-Cl- flux in human red blood cells

1985 ◽  
Vol 249 (1) ◽  
pp. C124-C128 ◽  
Author(s):  
P. K. Lauf ◽  
C. M. Perkins ◽  
N. C. Adragna
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Blood Cells ◽  
Time Course ◽  
Transport Activity ◽  
Human Red Blood Cells ◽  
Atp Breakdown ◽  
The Difference ◽  
Metabolic Dependence ◽  
K Transport

The effects of incubation in anisosmotic media and of metabolic depletion on ouabain-resistant (OR) Cl--dependent K+ influxes stimulated by N-ethylmaleimide (NEM) were studied in human red blood cells using Rb+ as K+ analogue. The NEM-stimulated but not the basal Rb+-Cl- influx measured in phosphate-buffered anisosmotic media was found to be cell volume dependent. When cellular ATP, [ATP]c, was lowered to less than 0.10 of its initial level by exposure to nonmetabolizable 2-deoxy-D-glucose, the NEM-stimulated but not the basal Cl--dependent Rb+ influxes were abolished. Metabolically depleted red blood cells subsequently repleted by incubation in glucose plus inosine regained the NEM-inducible Rb+ (K+) transport activity. The difference in the time course of ATP breakdown and Rb+ influx inhibition suggests that energization of the NEM-stimulated Rb+ flux by metabolism may involve factors additional to ATP.

scholarly journals Reappraisal of diffusion, solubility, and consumption of oxygen in frog skeletal muscle, with applications to muscle energy balance.

1985 ◽  
Vol 86 (1) ◽  
pp. 105-134 ◽  
Author(s):  
M Mahler ◽  
C Louy ◽  
E Homsher ◽  
A Peskoff
Keyword(s):  
Diffusion Equation ◽  
Time Course ◽  
Atp Hydrolysis ◽  
Rana Temporaria ◽  
Direct Method ◽  
Diffusion Method ◽  
Sartorius Muscle ◽  
O2 Consumption ◽  
Dimensional Diffusion ◽  
Frog Sartorius

Previously we tested the validity of the one-dimensional diffusion equation for O2 in the excised frog sartorius muscle and used it to measure the diffusion coefficient (D) for O2 in this muscle and the time course of its rate of O2 consumption (Qo2) after a tetanus (Mahler, 1978, 1979, J. Gen. Physiol., 71:533-557, 559-580, 73:159-174). A transverse section of the frog sartorius is in fact well fit by a hemi-ellipse with width divided by maximum thickness averaging 5.1 +/- 0.2. Using the previous techniques with the two-dimensional diffusion equation and this hemi-elliptical boundary yields a value for D that is 30% smaller than reported previously; the revised values at 0, 10, and 22.8 degrees C are 6.2, 7.9, and 10.8 X 10(-6) cm2/s, respectively. After a tetanus at 20 degrees C, Qo2 rose quickly to a peak and then declined exponentially, with a time constant (tau) approximately 15% faster than that reported previously; tau averaged 2.1 min in Rana temporaria and 2.6 min in Rana pipiens. A technique was devised to measure the solubility (alpha) of O2 in intact, respiring muscles, and yielded alpha (muscle)/alpha (H2O) = 1.26 +/- 0.04. With these modifications, the values for O2 consumption obtained with the diffusion method were in agreement with those measured by the direct method of Kushmerick and Paul (1976, J. Physiol. [Lond.]., 254:693-709). Using results from both methods, at 20 degrees C the ratio of phosphorylcreatine split during a tetanus to O2 consumption during recovery ranged from 5.2 to 6.2 mumol/mumol, and postcontractile ATP hydrolysis was estimated to be 13.6 +/- 4.1 (n = 3) nmol/mumol total creatine.

scholarly journals Ca(2+)-blockable, poorly selective cation channels in the apical membrane of amphibian epithelia. Tetracaine blocks the UO2(2+)-insensitive pathway.

1993 ◽  
Vol 101 (1) ◽  
pp. 103-116 ◽  
Author(s):  
L Desmedt ◽  
J Simaels ◽  
W Van Driessche
Keyword(s):  
Urinary Bladder ◽  
Time Course ◽  
Rana Temporaria ◽  
Noise Analysis ◽  
Inhibitory Effect ◽  
The Other ◽  
Cation Channels ◽  
Toad Urinary Bladder ◽  
Amphibian Epithelia ◽  
Microelectrode Measurements

We examined the effect of the local anesthetic tetracaine on the Ca(2+)-blockable, poorly selective cation channels in the isolated skin of Rana temporaria and the urinary bladder of Bufo marinus using noise analysis and microelectrode impalements. Experiments with frog skin demonstrated that mucosal concentrations of the compound up to 100 microM did not affect the Na+ current through type S channels (slowly fluctuating, UO2(2+)-blockable channels) and the associated noise. On the other hand, 20 microM mucosal tetracaine already suffices to inhibit approximately 50% of the current carried by Cs+ and Na+ through channel type F (fast fluctuating, UO2(2+)-insensitive channel) and So of the associated Lorentzian component. With 100 microM of the inhibitor the current and So values were reduced by at least 70-80%. The time course of the response to serosal tetracaine was markedly slower and the effects on the current and So were smaller. Possible effects on the basolateral K+ conductance were excluded on the basis of the lack of response of transepithelial K+ movements to 100 microM tetracaine. UO2(2+) and tetracaine together blocked the poorly selective cation pathways almost completely. Moreover, both agents retain their inhibitory effect in the presence of the other. In toad urinary bladder, the Ca(2+)-blockable channel is also tetracaine blockable. The concentration required for half-maximal inhibition is approximately 100 microM in SO4(2-) and approximately 20 microM in Cl-. The data with tetracaine complement those obtained with UO2(2+) and support the idea that the Ca(2+)-blockable current proceeds through two distinct classes of cation channels. Using tetracaine and UO2(2+) as channel-specific compounds, we demonstrated with microelectrode measurements that both channel types are located in the granulosum cells.

scholarly journals Energetics of Shortening Muscles in Twitches and Tetanic Contractions

1973 ◽  
Vol 62 (6) ◽  
pp. 663-676 ◽  
Author(s):  
Earl Homsher ◽  
Jack A. Rall
Keyword(s):  
Heat Production ◽  
Rana Pipiens ◽  
Energy Liberation ◽  
Mechanical Relaxation ◽  
The Difference ◽  
Activation Heat

Shortening heat was defined by Hill as the "difference between heat produced when shortening occurs and that produced in a similar contraction without shortening." For the tetanus the "similar contraction" was an isometric one at or near lo. By contrast, in a twitch the "similar contraction" was one in which only activation heat was produced. The applicability of Hill's concept of the shortening heat has been reexamined in both the twitch and tetanus of Rana pipiens semitendinosus muscles. Results of this investigation confirm the existence of an extra heat production accompanying shortening in the twitch and tetanus. In both cases, this shortening heat was proportional to distance shortened and relative afterload. However, at a given afterload the amount of shortening heat produced per distance shortened was greater in the twitch than the tetanus. This difference suggests that the base lines or "similar contractions" employed for the twitch and tetanus are not equivalent. The discrepancy is not remedied by utilizing in the tetanus the activation heat as the myothermic baseline and suggests that some heat producing factor(s) has been omitted in Hill's formulation of the shortening heat. Finally, the existence of Hill's feedback heat, an energy liberation associated with the presence of tension during mechanical relaxation, was not confirmed. This result strongly indicates that relaxation is energetically passive.

scholarly journals The time-course of energy balance in an isometric tetanus.

1979 ◽  
Vol 73 (5) ◽  
pp. 553-567 ◽  
Author(s):  
E Homsher ◽  
C J Kean ◽  
A Wallner ◽  
V Garibian-Sarian
Keyword(s):  
Energy Balance ◽  
Chemical Reaction ◽  
Isometric Contraction ◽  
Time Course ◽  
Rana Temporaria ◽  
Isometric Contractions ◽  
Chemical Changes ◽  
Rate Of Evolution ◽  
Work Production

Unpoisoned sartorius muscles of Rana temporaria were stimulated tetanically in isometric contractions lasting up to 20 s at 0 degrees C. The observed enthalpy (heat + work) production and the chemical changes in these contractions were measured, and a comparison was made between the observed enthalpy and the enthalpy that could be explained by the chemical changes. Like earlier workers, we found that the only net known reaction of energetic significance that occurred was dephosphorylation of n-phosphoryl creatine (PC), and we found a significant evolution of unexplained enthalpy (UE), a portion of the observed enthalpy which could not be explained by the extent of PC dephosphorylation. We measured the total quantity and the rate of production of the UE, and we found that its rate of evolution, which was most rapid during the first 750 ms of contraction, fell progressively to zero by the 8th s of contraction: i.e., after 8 s of contraction, all the observed enthalpy is adequately explained by PC dephosphorylation. The time-course of evolution of the UE was slower than that of the labile enthalpy (a component of the enthalpy evolved in isometric contraction whose rate of production declines exponentially at approximately 1 s-1). We conclude that, although the magnitudes of these enthalpy quantities may be similar, they are not derived from the same chemical reaction in muscle.

scholarly journals Radiocalcium Release by Stimulated and Potassium-Treated Sartorius Muscles of the Frog

1960 ◽  
Vol 43 (3) ◽  
pp. 481-493 ◽  
Author(s):  
A. M. Shanes ◽  
C. P. Bianchi
Keyword(s):  
Electrical Stimulation ◽  
Time Course ◽  
Rana Pipiens ◽  
Calcium Release ◽  
Sartorius Muscle ◽  
Entry And Exit ◽  
Potassium Depolarization ◽  
Rate Of Escape ◽  
The Individual ◽  
Stimulation Of

Stimulation of frog (Rana pipiens) sartorius muscle accelerates release of Ca45, but only during the period of stimulation. No appreciable difference is obtained in the calcium released per impulse whether stimulation is at a rate of 20/sec. or 0.5/sec. However, prior stimulation may appreciably increase the loss per impulse. In unfatigued muscles, the minimum amount of calcium liberated during an isotonic twitch is estimated to be about that previously calculated to enter, viz. 0.2 µµmole/cm2. The time course of radiocalcium release during potassium depolarization depends on the nature of the contracture. When contracture is isometric, the rate of escape is doubled and declines only slowly; if isotonic, the rate is quadrupled but declines in a few minutes to a level maintained at about double that before potassium. The minimal calcium release during the first 10 minutes of potassium treatment is estimated to be about the same in both cases and about one-half to one-third the uptake. This, and especially the close equality of calcium entry and exit during electrical stimulation, are pointed out as not necessarily inconsistent with a transitory net entry of calcium, comparable to the influx, into restricted regions of the individual fibers.

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