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.

scholarly journals Energy balance studies in frog skeletal muscles shortening at one-half maximal velocity.

1984 ◽  
Vol 84 (3) ◽  
pp. 347-359 ◽  
Author(s):  
E Homsher ◽  
T Yamada ◽  
A Wallner ◽  
J Tsai
Keyword(s):  
Skeletal Muscles ◽  
Maximum Velocity ◽  
High Energy ◽  
Sartorius Muscle ◽  
Maximal Velocity ◽  
High Energy Phosphate ◽  
The Mean ◽  
S Period ◽  
High Energy Phosphate Metabolism ◽  
Frog Sartorius

High-energy phosphate metabolism and energy liberated as heat and work were measured in 3-s tetani of frog sartorius muscle at 0 degree C. Two contraction periods were studied: (a) a 0.35-s period of shortening near half-maximum velocity beginning after 2 s of isometric stimulation, and (b) a 0.65-s isometric period immediately following the shortening. There were no significant changes in levels of ATP, ADP, or AMP in the two contraction periods. The observed changes in inorganic phosphate and creatine levels indicated that the only significant reaction occurring was phosphocreatine splitting. The mean rate of high-energy phosphate splitting during the shortening, 1.60 +/- 0.23 mumol X g-1 X s-1 (n = 24), was about fivefold higher than that in the 1-s period in the isometric tetanus, 0.32 +/- 0.11 mumol X g-1 X s-1 (n = 17), observed in our previous study. The mean rate in the post-shortening period, 0.46 +/- 0.13 mumol X g-1 X s-1 (n = 17), was not significantly different from that in the 1-s period in the isometric tetanus. A large amount of heat plus work was produced during the shortening period, and this could be accounted for by simultaneous chemical changes. In the post-shortening period, the observed enthalpy was also accounted for by simultaneous chemical reactions. Thus, the present result is in sharp contrast to that obtained from a similar study performed at a shortening at Vmax, where an enthalpy excess was produced during shortening and an enthalpy deficit was produced during the period following the shortening.

Effect of hyperventilation on dynamics of cerebral energy metabolism

1975 ◽  
Vol 228 (6) ◽  
pp. 1862-1867 ◽  
Author(s):  
K Kogure ◽  
R Busto ◽  
A Matsumoto ◽  
P Scheinberg ◽  
OM Reinmuth
Keyword(s):  
Energy Metabolism ◽  
Closed System ◽  
Energy Production ◽  
Energy Charge ◽  
High Energy ◽  
Utilization Rate ◽  
High Energy Phosphates ◽  
High Energy Phosphate ◽  
Cerebral Energy Metabolism ◽  
Extreme Degree

Hypocapnia of moderate and extreme degree (Paco2 21.1 and 13.5 torr, respectively)was induced by hyperventilation in rats subjected to the closed system of Lowry inorder to evaluate the effects on utilization rate of cerebral energy metabolites. The tissue levels of high-energy phosphates and calculated intracellular pH did not change, whereas glucose, pyruvate, and lactate increased significantly. The La/Pyratio and NADH/NAD-+ RATIO BOTH INCREASED IN PROPORTION TO THE DEGREE OF HYPOCAPNIA.Utilization rates of glucose, glycogen, and ATP were all significantly reduced by hypocapnia, whereas the utilization rate of phosphocreatine was increased. The rate oftotal high-energy phosphate use was also diminished in proportion to the degree of hypocapnia. The constant value of the energy charge (0.94 plus or minus 0.01) indicates that the energy production rate might also be reduced by hyperventilation; thus the intermediate metabolics and substrates increased. It is concluded that extreme hypocapnia reduces the rate of cerebral energy metabolism significantly.

When Does the Lung Die? Time Course of High Energy Phosphate Depletion and Relationship to Lung Viability after "Death"

1995 ◽  
Vol 59 (4) ◽  
pp. 468-474 ◽  
Author(s):  
Andrea M. D'Armini ◽  
Eugene J. Tom ◽  
Charles S. Roberts ◽  
David C. Henke ◽  
John J. Lemasters ◽  
...  
Keyword(s):  
Time Course ◽  
High Energy ◽  
High Energy Phosphate ◽  
Phosphate Depletion

Energy Metabolism of the Skeletal Muscle of Genetically Dystrophic Hamster

1972 ◽  
Vol 50 (5) ◽  
pp. 550-556 ◽  
Author(s):  
Naranjan S. Dhalla ◽  
Margaret Fedelesova ◽  
Ivan Toffler
Keyword(s):  
Energy Metabolism ◽  
Skeletal Muscles ◽  
Energy Production ◽  
Creatine Phosphokinase ◽  
Adenine Nucleotides ◽  
Creatine Phosphate ◽  
High Energy ◽  
Dystrophic Muscle ◽  
Glycerophosphate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase

The hind leg skeletal muscles of about 215-day-old genetically dystrophic hamsters (BIO strain 14.6) were found to contain subnormal concentrations of creatine phosphate, ATP, total adenine nucleotides, and NAD+ in comparison with those from the control animals. On the other hand, the levels of lactate, NADH, and NADPH were elevated without any significant changes in pyruvate, AMP, ADP, and NADP+ in the dystrophic muscle. The ratios of ATP/ADP and ATP/AMP were decreased and those of lactate/pyruvate, NADH/NAD+, and NADPH/NADP+ were increased in the dystrophic muscle. There are a number of similarities between the dystrophic and asphyxiated muscles with respect to energy metabolism; however, the possibility is not ruled out at present that the hypoxic-like changes in energy metabolism of the dystrophic muscle are due to mechanisms other than oxygen lack. The activity of glucose-6-phosphate dehydrogenase was increased whereas the activities of α-glycerophosphate dehydrogenase, glyceraldehyde phosphate dehydrogenase, lactate dehydrogenase, myokinase, and creatine phosphokinase were decreased in the dystrophic muscle. On the basis of our earlier and present results it is suggested that changes in the high energy phosphate stores in the genetically dystrophic hamster muscle are due to defects in both the processes of energy production and utilization.

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.

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