PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “SARTORIUS MUSCLE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1975

Length-dependent optical diffraction pattern changes in frog sartorius muscle.

The length dependence of the laser light diffraction pattern produced by R. pipiens whole sartorius muscle has been examined at rest and during tetanic contraction. The muscle diffraction pattern was scanned by a vidicon camera; camera output was digitized and processed by an on-line digital computer to allow a real line display of a section through the diffraction pattern. Analysis of the first order diffraction line profiles yielded values for line amplitude, intensity, center of gravity, line width and percent dispersion. The calculated dispersion provided a measure of the muscle's sarcomere length distribution. First order line amplitudes and intensities were observed to increase, then decrease, with progressive stretch from 1.0 to 1.3 reference length. The percent dispersion among sarcomeres in resting muscle averaged 11% and was approximately proportional (coefficient = .0341) to length. The amplitude and intensity of zero and first order diffraction lines decreased during tetanus, while the line widths and dispersions increased. First order line intesity during tetanus was maximum at about the same length as during rest, i.e., at approximately 2.5 mu sarcomere length. Sarcomere dispersion increased by about 6% during tetanus.

Animals↗
PubMed1989

Muscarinic inhibition of quantal transmitter release from the magnesium-paralysed frog sartorius muscle.

The existence of presynaptic muscarinic acetylcholine receptors on motor nerve terminals of the isolated frog sartorius muscle was investigated. The modulatory role of these receptors was studied by observing the effects of muscarinic ligands on the frequency of miniature endplate potentials and on the quantal content of endplate potentials. The agonist oxotremorine reduced in concentration-dependent fashion the frequency of spontaneous potentials and the amplitude of evoked potentials. Also, high concentrations of oxotremorine depolarized the postsynaptic membrane and reduced the amplitude of the miniature endplate potentials. The depolarizing action of the drug was blocked by D-tubocurarine. The muscarinic antagonist atropine attenuated agonist-induced reductions in endplate potential amplitude and miniature endplate potential frequency but did not affect the depression in amplitude of the spontaneous potentials evoked by oxotremorine. It is concluded that activation of presynaptic muscarinic receptors inhibits the release of acetylcholine from motor nerve terminals. Atropine itself had no effect on the quantal content of evoked potentials or on the frequency of spontaneous potentials suggesting that the nerve terminal is not affected by non-quantal acetylcholine.

Acetylcholine↗
PubMed1983

Action of insulin on the transport of 3-O-methylglucose in frog sartorius muscles.

The initial rate of entry of 3-O-methyl-D-glucose into isolated frog sartorius muscles was measured at various concentrations of substrate, at 0, 9, 19, or 29 degrees C, after prior incubation at 19 degrees C with a maximally stimulating concentration of insulin. Control muscles were treated similarly, except for the omission of insulin. A saturable transport system provided for most of the entry of 3-O-methylglucose into muscle cells, but a small amount of penetration occurred by a nonsaturable route. The major effect of insulin was to produce a large increase in activity of the suturable system. The Vmax of entry increased, but there was no significant change in the apparent Km. The ratio of insulin-stimulated to basal Vmax was 10 when transport was measured at 29 degrees C but was 22 at 0 degrees C. These findings support the hypothesis that, although a large part of the effect of insulin on sugar transport can be accounted for by an increase in the number of functional transporters in the plasma membrane, there is a separate hormonal effect that permits a relatively greater activity of transporters at lower temperatures, compared with control rates. An additional effect of insulin was to produce a small but definite increase in the entry of sugar by the nonsaturable transport system.

3-O-Methylglucose↗
PubMed1984

The effect of chlorpromazine and dibucaine on phospholipid metabolism in the frog sartorius muscle.

The effect of cationic amphiphilic drugs, chlorpromazine and dibucaine, on phospholipid metabolism in the frog sartorius muscle was studied at concentrations affecting excitation-contraction coupling. Labelling patterns of phospholipids using 32P orthophosphate were determined. The drugs at a concentration of 3.10(-4) mol/l inhibited the synthesis of phosphatidylcholine and phosphatidylethanolamine and stimulated the synthesis of phosphatidylinositol and phosphatidylserine. At the 3.10(-3) mol/l concentration the drugs blocked the synthesis of all phospholipids without appreciably affecting their degradation. The effect of cationic amphiphilic drugs was independent of the presence of Ca2+ or K+ ions in the media, however, basal labelling of phospholipids was affected by withdrawal of Ca2+ or K+ ions.

Animals↗
PubMed1990

Force during stretch and shortening of frog sartorius muscle: effects of intracellular acidification due to increased carbon dioxide.

The force-velocity relation of frog sartorius muscle was observed during slow stretch and during shortening in solutions with and without CO2 at extracellular pH (pHo) 6.9 and pHo 7.5 (5 degrees C). Less force was produced with CO2 than without CO2 during stretch, during shortening, and under isometric conditions. Compared with pHo 7.5, the effects were greater at pHo 6.9, where the concentration of CO2, a permeant acid, was greater and would cause a greater acidification of intracellular pH (pHi). The reduction of force caused by CO2 was smaller during stretch than during shortening or isometric contraction. This result indicates that the crossbridge states specific to stretch retain their ability to produce force better under acidic conditions than those characteristic of shortening and isometric conditions. This difference between stretch and shortening suggests that there may be compensating changes in the pattern of motor unit activity during fatigue in vivo.

Animals↗
PubMed1977

Chemical energetics in repeated contractions of frog sartorius muscles at 0 degrees C.

1. Recovery oxygen consumption (DeltaO(2)) was measured in aerobic, unpoisoned frog sartorius muscles at 0 degrees C following a series of repeated tetani.2. For a series of tetani having nearly identical tension-time integrals, DeltaO(2) was dependent on the interval between tetani and reached a maximal value for intervals equal to or greater than 200 sec.3. For a series of tetani at short (5 sec) intervals, DeltaO(2) was not distinguishable from DeltaO(2) following a single long tetanus having a tension-time integral similar to that of the sum of the series.4. A model is proposed to account for these observations in terms of the initial chemical reactions (Delta approximately P) including a saturable non-steady state reaction which utilizes about 1 mumole Delta approximately P/g and which is superimposed on an energy utilization proportional to the tension-time integral. Measurements of DeltaO(2) and Delta approximately P as functions of tetanic duration and interval between tetani are consistent with such a model.5. These experiments show that, in addition to parameters usually considered, the previous contractile history of a muscle plays a significant role in determining the chemical energy cost of an isometric contraction.

Animals↗
PubMed1984

Polyneuronal innervation and quantal transmitter release in formamide-treated frog sartorius muscles.

The incidence of focal polyneuronal innervation was measured at end-plates in normal and reinnervated sartorius muscles from Rana pipiens either in the presence of curare to partially block neuromuscular transmission or in normal Ringer solution after pre-treatment with formamide to block excitation-contraction coupling. The incidence of polyneuronal innervation estimated with curare in normal muscles during the winter (19%) was significantly higher than the incidence in summer (9%). After formamide treatment, large end-plate potentials (e.p.p.s) and miniature e.p.p.s (m.e.p.p.s) could be recorded in Ringer solution containing physiological levels of Ca2+. For both normal and reinnervated muscles, higher levels of polyneuronal innervation could be recorded in normal Ringer solution after formamide treatment compared with levels measured in the presence of curare. This was true whether randomly selected end-plates or the same group of identified end-plates were examined before and after formamide treatment. Quantal content in normal Ringer solution containing 1.8 mM-Ca2+ was measured as the ratio of mean e.p.p. amplitude divided by mean m.e.p.p. amplitude. In randomly selected samples of normal end-plates the range of quantal contents seen was 18-112 (mean 50). For reinnervated end-plates 60 days after nerve crush, quantal contents were 6-181 (mean 54). It was concluded that formamide pre-treatment is a more sensitive technique for estimating the incidence of focal polyneuronal innervation and that, with appropriate controls, it can be used to measure quantal transmitter release accurately without using synaptic blocking agents.

Action Potentials↗
PubMed1975

Properties of sarcolemmal delayed rectification in glycerol-treated fibers of frog sartorius muscle.

Total current-voltage relations were analyzed on nine glycerol-treated surface fibers of frog sartorius muscles in tetrodotoxin-containing isotonic normal Ringer solution. The results indicate that delayed rectification occurs in the sarcolemma on large depolarization and that delayed rectification is only partially inactivated during 1 sec of depolarization and not converted into anomalous rectification. The time to peak, the time course of inactivation and the potassium activation potential determined in glycerol-treated fibers were comparable to those analyzed previously in intact fibers. The value of the conductance increase during delayed rectification in glycerol-treated fibers appeared to be smaller than that in intact fibers.

Animals↗
PubMed1982

Segmental length changes in stimulated frog sartorius muscle during dynamic mechanical responses.

The nonuniformity of dynamic mechanical responses along the length of stimulated frog sartorius muscle was examined by recording the length changes of muscle segments by means of streak photography. During isometric force development, the central or the pelvic end segment tended to shorten due to the stretching of the other segments. In muscles showing a marked nonuniformity in the segmental length changes occurring during isometric force development, there was also a marked nonuniformity in the segmental length changes occurring during stretches or releases applied at the plateau phase of an isometric tetanus. Marked nonuniform segmental length changes were also observed during afterloaded twitches and tetani. These results indicate that great care should be taken of the muscle segmental nonuniformity in heat and X-ray diffraction studies in which measurements are made using data obtained from a limited region of muscle. During the course of slow stretches or releases applied to tetanized muscles, the tibial and segment exhibited much smaller relative lengthening or shortening than the other segments when it had been appreciably stretched by the other segments during isometric force development. This might be associated with the formation of "locked-on" cross-links in the stretched segment.

Animals↗
PubMed1978

[Mediator liberation at the myoneural junctions of the frog sartorius muscle when axoplasmic transport has been disrupted with colchicine].

Colchicine application to the nerve innervating the frog sartorius muscle leads to reduction of the differences in functional condition of the myoneural synapses of this muscle by the signs of quantum content of the end plate potential (EPP) and by the changes of the EPP amplitudes in high frequency stimulation. Along with this there occurs a rarefaction of the frequency of miniature potential of the end plate, and reduction of its amplitude. Apparently, the latter is caused by reduction of effective resistance of the postsynaptic membrane. Changes of the induced and spontaneous secretion of the mediator are connected with disturbances of the axoplasmic transport just in the somatic nerve fibers.

Animals↗
PubMed1994

Canine model for treatment of faecal incontinence using transposed and electrically stimulated sartorius muscle.

A neosphincter was successfully created around each end of a Thiry-Vella loop in five dogs using transposed sartorius muscle to study new treatments for faecal incontinence. One of these dynamic neosphincters in each dog was electrically trained for 8 weeks while the other served as a control. Muscle biopsies demonstrated an increase in type 1 fatigue-resistant fibres from a median of 49 (range 37-54) per cent before electrical stimulation to 78 (range 53-99) per cent 8 weeks later in the stimulated sartorius neosphincters (P < 0.05), whereas the percentage of type 1 fibres in control neosphincters increased only slightly. Retention times of saline increased from a median of 10 (range 5-50)s before to 340 (range 100-470)s after electrical stimulation (P < 0.05) but also increased in control neosphincters (to 370 (range 330-1200)s); this may indicate that electrical stimulation immediately increases acute retention times. It is concluded that construction of a neosphincter is technically feasible with preservation of muscle morphology and that stimulation induces morphological and functional changes towards the characteristics of the external anal sphincter.

Anal Canal↗
PubMed1971

The sodium-potassium exchange pump. II. Analysis of Na + -loaded frog sartorius muscle.

A model for the Na-K exchange pump was applied to data on Na(+)-loaded frog sartorius muscle, and was used to relate the rate of adenosine triphosphate (ATP) hydrolysis to the electrical properties of the cell membrane. Membrane hyperpolarization was considered to arise from an electrical current which was produced by the hydrolysis reaction coupled to ion movements, and which flowed across the membrane. The reaction rate, as calculated from hyperpolarization, agreed with direct measurements of ATP hydrolysis and with the rate estimated from Na(+) tracer efflux studies. Although Na(+) is actively extruded, the model showed that K(+) is inwardly transported if the potassium permeability of the membrane is less than about 6.6 x 10(-6) cm/sec, as is suggested by resistance data. Calculations indicated that the reaction conductance L(rr) was relatively constant when compared with the reaction rate and reaction free energy for large changes in internal and external ionic concentrations. Its value agreed with the value obtained from the dependence of Na(+) tracer efflux on external K(+). A set of experiments was suggested which would provide a more complete interpretation of the data.

Adenosine Triphosphate↗
PubMed1990

Shape and orientation of arterial loops in cat sartorius muscle.

A method is described to quantify the shape and orientation of vascular loops (arcades). Shape is characterized by an ellipticity factor, calculated from area and perimeter values. Orientation is measured as the angle formed by the great axis of the loop with the muscle fibers. These parameters were calculated for 772 arteriolar loops of the cat sartorius muscle. The results show that, on the average, the ellipticity factor is a linear function of the number of segments. The observed values change in the opposite direction from the expected values for regular polygons. Simple calculations are presented to rectify this discrepancy. Most loops are oriented parallel to the muscle fibers.

Animals↗
PubMed1964

TRACER AND NON-TRACER POTASSIUM FLUXES IN FROG SARTORIUS MUSCLE AND THE KINETICS OF NET POTASSIUM MOVEMENT.

Experiments were performed to test the applicability of permeability kinetics to whole frog sartorius muscle using K(42) ions as tracers of potassium flux. The whole muscle was found to obey closely the kinetic laws expected to hold for single cellular units in which the potassium fluxes are membrane-limited and intracellular mixing is rapid enough not to introduce serious error. In a 5 mM K Ringer's solution, potassium efflux was very nearly equal to influx when the rate constant for K(42) loss was applied to the whole of the muscle potassium. Over a fairly wide range of external potassium concentration, the assumed unidirectional fluxes measured with tracer K(42) showed good agreement with net potassium changes determined analytically. The specific activity of potassium lost from labeled muscles to an initially K-free Ringer's solution was measured as a test of the adequacy of intracellular mixing. The results were those expected for a population of cells with uniformly distributed intracellular K(42). A small deviation was encountered which can be attributed either to a dispersion of fiber sizes in the sartorius or to a possible small additional cellular compartment in each individual fiber. The additional cellular compartment, should it exist, contains from 0.5 to 1 per cent of the muscle potassium. This is evidently not large enough to interfere seriously with the applicability of permeability kinetics to the whole muscle.

Animals↗
PubMed1987

X-ray diffraction studies of the structural state of crossbridges in skinned frog sartorius muscle at low ionic strength.

Low-angle X-ray diffraction diagrams were obtained from chemically skinned frog sartorius muscles under low ionic strength relaxing conditions. Experiments on single muscle fibres from rabbit muscle and on muscle proteins in solution have suggested the presence of a 'low ionic strength attached state' of the myosin crossbridges to actin, in which the overall ATP splitting and force-generating cycle is still blocked. This opened up the possibility that structural information about one of the intermediate states in the crossbridge cycle might be obtained under these conditions. Using synchrotron radiation as a high intensity X-ray source we were able to record the appropriate diffraction diagrams with short exposure times and were able to compare the same muscles at normal and at low ionic strength. Changes in the intensities of the equatorial reflections an increase in the 143 A meridional intensity can be interpreted in a similar way. However, these attached bridges do not give rise to changes in the actin-based layer line reflections, nor is their presence associated with a weakening of the myosin layer line pattern. These results provide further evidence for the existence of bound states of crossbridges, in which their orientation relative to actin is not sharply defined.

Actins↗