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PubMed1978

Characterization of frog muscle mitochondria.

Studies on oxidative phosphorylation revealed that, in frog skeletal muscle mitochondria (SKMM) from the thigh, the adenosine diphosphate/oxygen ratio (ADP/O) was 2.8 +/- 0.1 SE, and the respiratory control ratio was 9.5 +/- 0.9, with pyruvate/malate as the substrate. Oxygen uptake rate (Qo2) was 225 mumol O2 per minute per gram mitochondrial protein +/- 13; phosphorylation rate (ADP/O X Qo2 X 2) was 1,230 mumol ADP phosphorylation per minute per gram mitochondrial protein +/- 77; and the phosphorylation capacity (phosphorylation rate times tissue mitochondrial protein content) was 3.6 mumol ADP phosphorylated per gram wet weight of muscle +/- 0.2. Tissue mitochondrial protein content was determined by the measurement of nicotinamide adenine dinucleotide (NADH) oxidase activity. Electron microscopy (EM) revealed intact, isolated, energized twisted mitochondria of a condensed form. Frog sartorius muscle mitochondria gave similar oxidative phosphorylation parameters when investigated independently of the rest of the thigh. These values of SKMM respiration from the frog are similar to those values obtained from pigeon and rabbit heart and rat skeletal muscles. However, because of the low NADH-oxidase activity indicating reduced mitochondrial content (this was verified in low-magnification EM pictures), phosphorylation capacity was significantly reduced in frog skeletal muscle mitochondria.

Animals↗
PubMed1998

Infrared thermography of bullfrog skeletal muscle at rest and during an isometric tetanus.

Heat production in skeletal muscle has been studied with a thermopile consisting of several thermocouples in contact with muscle surface, and the experimental results have been interpreted on the assumption that heat is produced in a uniform manner. In the present study we have examined the temperature distribution of bullfrog sartorius muscle by the technique of infrared thermography, in which muscle temperatures at various regions can be measured and displayed as a thermogram on the monitor screen without thermal contact. It was found that in the muscle at rest and during an isometric tetanus, the temperature was not uniform, but differed from region to region. The amount of heat production during an isometric tetanus also differed from region to region, but the time course of heat production was nearly uniform in every region. By putting position markers on the muscle surface, it was possible to record muscle segment length changes together with temperature changes. It was found that during an isometric tetanus, the tibial region was stretched by the other regions, and the amount of heat produced was significantly greater in the other regions than in the tibial region. The application of infrared thermography in muscle energetics studies seems promising if the sensitivity of infrared detectors is improved.

Animals↗
PubMed1983

The influence of amino-reactive substances on contraction threshold of frog skeletal muscle.

The action of the amino-reactive substances pyridoxal phosphate, 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid and 2,4,6-trinitrobenzene sulfonic acid on the contraction threshold, taken as parameter for the initiation of contraction, was investigated in fibers of the sartorius muscle of the frog. The contraction threshold was shifted by 1 to 11 mV to more negative potentials with 1 to 20 mM PDP. Similar shifts from 2 to 17 mV were produced by 0.66 to 20 mM SITS. The threshold shift was only partially reversible. The shift of the contraction threshold obtained with 2 mM SITS was nearly constant at different [Ca2+]o and [Mg2+]o from 1.5 to 50 mM with a tendency to increase at higher divalent cation concentration. TNBS had no effect on the contraction threshold. The action of PDP and SITS on the contraction threshold was successfully described by the surface charge model used earlier to explain the effect of lanthanum, neuraminidase and ruthenium red on the contraction threshold (M. Dörrscheidt-Käfer, Pfluegers Arch. 380:171-179, 181-187, 1979; J. Membrane Biol. 62:95-103, 1981). Here it was assumed that PDP and SITS bind to positive fixed charges on the surface of the T-tubular wall. This results in a shift of the calculated surface potential to more negative values which is thought to account for the measured shift of the contraction threshold.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1979

Allometric radial growth in muscle, comparing fibres with strong and with weak adenosine triphosphatase activity.

A large flock of male and female white turkeys (Meleagris gallopavo) was reared for 22 weeks after hatching. At two weeks intervals small groups of birds were removed from the flock and killed. Samples of sartorius muscles were taken from the bird nearest the mean weight for its group. Transverse frozen sections were tested for ATPase activity by calcium method at pH 9.4. Fibres were separated into two categories (strong-ATPase and weak-ATPase) and their mean minimum diameters were measured with a micrometer scale in the microscope eyepiece. Mean minimum diameters of different fibre types were compared using the logarithmic form of Huxley's allometric growth equation. Weak-ATPase fibres grew at a relatively faster rate than strong-ATPase fibres in both males and females (k = 1.12, P less than 0.01 and k = 1.14, P less than 0.01 respectively). Transition of muscle fibres from one histochemical type to another was not detected, so that differences in the rate of increase of mean diameters of different fibre types were attributed to allometric radial growth. The possibility that transitional fibres might make some contribution cannot, however, be totally ignored.

Adenosine Triphosphatases↗
PubMed1977

Ca+2-accumulating components in developing skeletal muscle.

This ultrastructural study on the localization of Ca+2 in developing skeletal muscle indicates that the formation of calcium-accumulating components begins during embryonic development. Both oxalate and pyroantimonate techniques are used to localize Ca+2 in distinct cellular components of chick pectoral and sartorius muscles. Two major sites for Ca+2 accumulation are present in ultrathin sections of embryonic and post-embryonic muscles: the terminal cisternae of the sarcoplasmic reticulum and specific lines in the I-bands. Calcium oxalate-accumulating vesicles are present in the smallest recognizable myotubes at the twelfth day of incubation, but calcium-accumulating components are not seen at myofibrillar I-band sites until the fourteenth to seventeenth days of incubation. The fact that myofibrils first form and later in development accumulate a Ca+2-binding component suggests that this Ca+2-binding component is not necessary for the formation of myofibrils, but is added to myofibrils before hatching to serve a probable regulatory role in contraction.

Age Factors↗
PubMed1988

Effects of internal Na and external K concentrations on Na/K coupling of Na,K-pump in frog skeletal muscle.

To clarify the dependency of the Na/K coupling of the Na,K-pump on internal Na and external K concentrations in skeletal muscle, the ouabain-induced change in membrane potential, the ouabain-induced change in Na efflux and the membrane resistance were measured at various internal Na and external K concentrations in bullfrog sartorius muscle. Upon raising the internal Na concentration from 6 mmol/kg muscle water to 20 mmol/kg muscle water, the magnitude of the ouabain-induced change in membrane potential increased about eightfold and the magnitude of the ouabain-induced change in Na efflux increased about fivefold while the membrane resistance was not significantly changed. As the external K concentration increased from 1 to 10 mM, the magnitude of the ouabain-induced change in membrane potential decreased (1/5.5 fold), while the magnitude of the ouabain-induced change in Na efflux increased (about 1.5-fold). The membrane resistance decreased upon raising the external K concentration from 1 to 10 mM (1/2-fold). These observations imply that the values of the Na/K coupling of the Na,K-pump increases upon raising the internal Na concentration and decreases upon raising the external K concentration.

Animals↗
PubMed2004

A prospective, randomized study analyzing sartorius transposition following inguinal-femoral lymphadenectomy.

OBJECTIVES: Based on the reduced morbidity seen in our retrospective study, we undertook a prospective, randomized trial to determine whether transposition of the sartorius muscle improves post-operative morbidity in women with squamous cell carcinoma of the vulva undergoing inguinal-femoral lymphadenectomy. METHODS: Patients with squamous carcinoma of the vulva requiring inguinal-femoral lymphadenectomy were randomized to undergo sartorius transposition or not. All patients received perioperative antibiotics, DVT prophylaxis, and closed suction surgical site drainage. Outcomes assessed include wound cellulitis, wound breakdown, lymphocyst formation, lymphedema, and/or rehospitalization. Cohorts were compared using Fisher's exact test. Baseline characteristics were compared using Student's t test or Fischer's exact test as appropriate. Logistic regression was used to assess the impact of sartorius transposition, after adjusting for other factors. RESULTS: From June 1996 to December 2002, 61 patients underwent 99 inguinal-femoral lymphadenectomies, 28 with sartorius transposition, and 33 without. The mean (SD) age for controls and patients undergoing sartorius transposition was 63.5 (15.2) and 73.8 (13.7) years, respectively (P < 0.05). There were no statistically significant differences in BSA, tobacco use, co-morbid medical conditions, past surgical history, medication use, size of incision, duration of surgery, number of positive lymph nodes, pathologic stage, pathologic grade, pre- or postoperative hemoglobin, or length of hospitalization. There were no statistically significant differences in the incidence of wound cellulitis, wound breakdown, lymphedema, or rehospitalization. The incidence of lymphocyst formation was increased in the sartorius transposition group. After adjusting for age, however, the groups appeared similar. CONCLUSIONS: Sartorius transposition after inguinal-femoral lymphadenectomy does not reduce postoperative wound morbidity.

Aged↗
PubMed1989

Calbindin-immunoreactive sensory neurons of dorsal root ganglion project to skeletal muscle in the chick.

In the chicken dorsal root ganglia, two neuronal subpopulations referred to as A1 and B1 share in common an immunoreactivity to antisera raised to calbindin D-28k but are distinguished by their cytological and ultrastructural characteristics. To determine the peripheral targets innervated by calbindin-immunoreactive neurons in lumbosacral dorsal root ganglia, cryostat sections of various hindlimb tissues were treated with anticalbindin antisera. Calbindin-immunostained axons were clearly detected in skeletal muscle. Large myelinated nerve fibres and afferent axon terminals in neuromuscular spindles were calbindin-immunoreactive; thin unmyelinated nerve fibres were also immunostained in nerve bundles of the perimysium. Since motoneurons and neurons of the autonomic nervous system were devoid of calbindin immunostaining, it was suggested that the immunoreactive axons found in skeletal muscle originate from sensory neurons expressing a calbindin immunoreaction in the dorsal root ganglia. This hypothesis was corroborated after introduction of wheat germ agglutinin coupled with horseradish peroxidase or colloidal gold particles into the sartorius muscle. The retrogradely transported tracer was collected only in ganglion cell bodies which displayed the ultrastructural characteristics of A1 and B1 sensory neurons. On the basis of calbindin immunoreaction and of tracer retrograde transport, it is concluded that ganglion cells of subclasses A1 and B1 contribute to the sensory innervation of skeletal muscle in the chicken.

Afferent Pathways↗
PubMed1982

Inhibitory action of high formamide concentrations on excitation-contraction coupling in skeletal muscle.

Strips of guinea pig ileum lose over 70% of their contractility when bathed in Krebs-Ringer solution containing 0.4-0.9 M formamide (FMD). This effect is not accompanied by an appreciable loss of tissue water and is totally reversed by washing the preparation in normal solution. Frog sartorius muscles also paralyze when immersed in Ringer containing FMD, but higher concentrations (1.0-2.0 M) and longer exposure times are required. Contractility is not recovered upon transferring these muscles to normal Ringer. However, the contractile proteins still respond to activator calcium as shown by the fact that these muscles still contract in the presence of caffeine. The membrane of muscles uncoupled by FMD retain electrical excitability, and neuromuscular transmission appears to be unimpaired. However, alterations in the early after-potential of the spikes suggest the occurrence of a sarcotubular disruption. Therefore, FMD appears to exert two separate effects on muscle: a reversible inhibition of contractility, as observed in ileal strips and an irreversible blockade due to an osmotic shock observed when frog muscles are returned to normal Ringer. The reversible effect is probably related to interference with the availability of activator calcium, since no marked inhibitory effects on the activities of the actomyosin-like and the calcium-dependent and -independent ATPases could be observed on FMD-treated subcellular fractions.

Adenosine Triphosphatases↗
PubMed1978

A time-resolved X-ray diffraction study of muscle during twitch.

1. A position sensitive X-ray counter was connected to a data-collection system which registered the outputs of the counter as a function of time. This enabled us to study time-dependent changes in the intensities of the equatorial reflexions from frog sartorius muscle during an isometric twitch. 2. The intensity ratio of the 1.0 and 1.1 equatorial reflexions (I1,0/I1,1) decreased during a twitch. The time at which the intensity ratio started to decrease coinsided approximately with the onset of tension development. No detectable change in the intensity ratio occurred during the latency relaxation. 3. The intensity ratio reached a minimum level approximately 90 msec before the peak of tension, and stayed at that level until the peak tension. 4. The intensity ratio returned to the 'resting' value 0.7--1.1 sec after the twitch tension had fallen to zero. 5. The observed decrease in the intensity ratio was interpreted as being caused by radial movements of the myosin projections from the vicinity of thick filaments to that of thin filaments. This leads us to conclude that, early in the rising phase of twitch tension, the number of myosin projections in the vicinity of thin filaments reaches the value obtained during a maximum isometric tetanus.

Animals↗
PubMed1991

Nicotinic pharmacology of anatoxin analogs. I. Side chain structure-activity relationships at peripheral agonist and noncompetitive antagonist sites.

Anatoxin analogs were designed to evaluate the importance of H-bonding, planarity, size and steric configuration of the anatoxin side chain moiety with regard to nicotinic potency and efficacy. This report examines the actions of these analogs on the somatic nicotinic acetylcholine receptor at two different loci: the agonist recognition site and the ion channel site. Agonist effects were evaluated using stimulation of contracture and radioligand binding competition for [125I]alpha bungarotoxin sites in Rana pipiens muscle, and stimulation of [3H]perhydrohistrionicotoxin binding and competition for [125I]alpha bungarotoxin sites in Torpedo californica electric organ. Antagonist effects were evident in the inhibition of neurally evoked twitch of the frog sciatic nerve-sartorius muscle preparation and in inhibition of [3H]perhydrohistrionicotoxin binding to Torpedo receptors. The affinity of these analogs for the agonist locus was consistently associated with activation of the AChR. Our results show that side chain steric configuration has an important role in affinity of the (+)-anatoxin-a analogs for the nicotinic acetylcholine receptor ion channel sites. Several analogs also revealed stereospecific noncompetitive actions. The (+)-anatoxin-a-related structures are important probes for characterizing both agonist and ion channel target sites on the peripheral nicotinic receptor.

Amphibian Venoms↗
PubMed1983

Interactions of phencyclidine with ion channels of nerve and muscle: behavioral implications.

Phencyclidine (1-(1-phenylcyclohexyl)piperidine [PCP]), a behaviorally active analogue (1-(1-m-aminophenylcyclohexyl)piperidine [m-amino-PCP]), and two behaviorally inactive analogues (1-(1-m-nitrophenylcyclohexyl)piperidine and 1-piperidinocyclohexanecarbonitrile) block neuromuscular transmission, depress the amplitude and rate of rise of directly elicited action potentials in frog sartorius muscle, and cause voltage- and concentration-dependent decreases of the peak end-plate current amplitude. This implies that all four compounds block the ion channel of the acetylcholine (ACh) receptors. Only PCP and m-amino-PCP prolong the action potential, block delayed rectification, potentiate muscle twitch, increase quantal content of end-plate potentials, and block K+-induced 86Rb+ efflux from rat brain synaptosomes. PCP also possesses central and peripheral antimuscarinic activity but is much less potent than 3-quinuclidinyl benzilate (QNB). Atropine, scopolamine, and QNB require much higher concentrations to induce behavioral alterations than to block muscarinic receptors. Thus PCP and some of its behaviorally active and inactive derivatives share two common effects, blockade of the nicotinic ACh receptor-ion channel complex and blockade of central and peripheral muscarinic receptors. The feature that apparently separates behaviorally active from inactive derivatives of PCP is their ability to block K+ conductance (gK) and thereby potentiate muscle twitch and increase the release of transmitters from central and peripheral synapses. The similarity between PCP-induced behavioral alterations and primary schizophrenia in humans raises the possibility of involvement of an altered gK in the human disease.

Action Potentials↗
PubMed1986

A possible involvement of cyclic AMP in the expression of desensitization of the nicotinic acetylcholine receptor. A study with forskolin and its analogs.

Forskolin, an activator of adenylate cyclase, and its analogs were studied on the nicotinic acetylcholine receptor-ion channel complex (AChR) of rat and frog skeletal muscles. At nanomolar concentrations, forskolin caused desensitization of the AChR located at the junctional region of innervated and the extrajunctional region of chronically denervated rat soleus muscles. The desensitization of the AChR occurred without alteration of the conducting state (channel lifetime, conductance or bursting) as shown by single channel currents. Accordingly, forskolin decreased the peak amplitude of the repetitive evoked endplate currents in frog sartorius muscles. These findings taken together with the good correlation found between the effects of forskolin and its analogs on the desensitization of the nicotinic AChR and their ability to activate adenylate cyclase suggested a possible involvement of phosphorylation of AChR via cyclic AMP on the desensitization process.

Acetylcholinesterase↗
PubMed1976

Twitch potentiation of skeletal muscle by physostigmine at different pH.

This report extends earlier research, done with external media at pH 7.2, to new studies at pH 6.4 and 8.4 as well as 7.2, to determine the roles of the protonated and neutral forms of physostigmine (a weak base with pKalpha = 8.2) in causing twitch potentiation of the frog sartorius muscle. Physostigmine, especially at relatively high pH (8.4) and concentration (1.5 mM), considerably blocks excitation. However, the results show in general that physostigmine potentiation increased peak contraction time and thereby indicate that potentiation is occurring in terms of prolongation of the active state. At pH 6.4 and 8.4, 1 mM physostigmine causes no change in the mechanical threshold of K depolarization contractures of toe muscles, as found previously at pH 7.2. Physostigmine increasingly prolongs the action potential as pH rises, i.e., in positive correlation with the twitch potentiation, thus indicating that this electrical change is the prime determinant of the potentiation.

Action Potentials↗
PubMed1981

Excitation-contraction uncoupling of striated muscle fibres by formamide treatment: evidence of detubulation.

A reportedly new technique of excitation-contraction uncoupling of frog skeletal muscle fibres was evaluated by low-frequency linear cable analysis and electron microscopy. Results indicate a similarity between the electrophysiological and ultrastructural effects of the formamide procedure and those obtained with conventional glycerol shock. Fibres in isolated frog sartorius muscles immersed in a frog Ringer's-formamide solution showed a rapid decline in twitch tension and a decrease in specific membrane capacitance, and disruption of the morphology of the transverse tubule system. These results are consistent with physical and electrical isolation of the transverse tubular network from the surface membrane of the muscle fibre ("detubulation"). However, reduction of twitch tension is marked in the formamide solution. Complete paralysis is only achieved following the return to normal Ringer's. Probably due to the greater membrane permeability of formamide, the technique requires less time and may be more reliable than the standard glycerol shock procedure.

Animals↗
PubMed1986

Microvascular pressure in venules of skeletal muscle during arterial pressure reduction.

It has been suggested from whole organ studies that the viscosity of blood in skeletal muscle venules varies inversely with flow over physiological flow ranges. If this is the case, the hydrostatic pressure gradient in venules should change less than flow as flow is altered. To test this hypothesis, pressure in venules of cat sartorius muscle was measured during stepwise arterial pressure reduction to 20 mmHg. Large vein pressure remained constant at about 5 mmHg. Average pressures in the large venules (40-185 microns) ranged from 13.6 to 10.0 mmHg. The difference between pressure in these venules and large vein pressure fell in proportion to the reduction in blood pressure and blood flow. Pressures in the smallest venules studied (25 microns) averaged 19.7 +/- 6.2 (SD) mmHg. The pressure difference between the smallest venules and the large vein fell less than the arteriovenous pressure difference or blood flow when arterial pressure was reduced. During reactive hyperemia the pressure gradient between the smallest venules and the large vein rose proportionately less than blood flow. The stability of pressure in the smallest venules is consistent with the hypothesis that blood viscosity varies inversely with flow rate.

Animals↗
PubMed1985

Simultaneous assessment of red cell perfusion in skeletal muscle by laser Doppler flowmetry and video microscopy.

The objective of this study was to compare temporal and spatial variations of the laser Doppler flowmeter output (V) with the corresponding variations of perfusion (cells/mm3 X mm/s) evaluated by video microscopy. The flowmetry and video microscopy sampled 2 mm3 (approx.) and 0.84 mm3 surface volumes of the sartorius muscle in anesthetized frogs, respectively. The overall ranges of the output and perfusion measurements were from 0.01 to 0.72 V and from 45 to 1404 cells/mm3 X mm/s. Within these ranges, temporal variations induced by muscle contraction correlated well (overall r = 0.91), but the spatial variations associated with the resting state correlated poorly (overall r = 0.45). When the penetration of the laser light was limited to 0.3-0.4 mm (to make the volumes sampled by both techniques more comparable) the overall r of the spatial comparison increased to 0.86. It is concluded that the flowmeter (1) is affected by red cell perfusion below the tissue depth of 0.3-0.4 mm, and (2) can follow both the temporal and spatial variations of red cell perfusion in the tissue examined.

Capillaries↗
PubMed1984

Effect of maternal dietary fat on skeletal muscle cellularity and satellite cell content of the porcine fetus at 110 days of gestation.

Crossbred gilts and sows were fed isocaloric diets that contained 0, 2.3, 12.8 or 29.7% poultry fat beginning at day 80 of gestation. At day 110 of gestation, fetuses were removed by Caesarean section. Maternal dietary fat did not influence fetal weight, sartorius muscle weight, length, composition, cellularity or satellite cell content. It was concluded that feeding diets high in fat during the last trisemester as exercised in this study did not influence the satellite cell content or cellularity of skeletal muscle.

Animals↗