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PubMed1988

Heterogeneity of microvascular response to ischemia in skeletal muscle.

The aim of this study was to use the video-microscopic approach to analyze simultaneously, at very low magnification, red cell velocity (VRBC) and density of perfused capillaries (CD) in an entire capillary network of a frog sartorius muscle before and after 3 s, 1 min and 30 min arterial occlusions. In 11 muscles studied, the 3 s occlusion caused a significant increase in the overall peak hyperemic VRBC and CD (from 0.14 +/- 0.08 to 0.28 +/- 0.16 S.D. mm/s, and from 104 +/- 41 to 126 +/- 42 S.D. cap/mm2). All muscles participated in this overall response. On average, 71% of capillaries per network showed hyperemia. The 1 min occlusion also caused significant increases in overall VRBC and CD (from 0.14 +/- 0.08 to 0.34 +/- 0.17 S.D. mm/s, and from 94 +/- 44 to 123 +/- 44 S.D. cal/mm2). In contrast to the 3 s response, only 9 out of 11 muscles participated in this response, with an average capillary participation of 80%. The 30 min occlusion caused a significant increase in overall VRBC (from 0.13 +/- 0.07 to 0.24 +/- 0.17 S.D. mm/s) but no change in CD. Only 6 out of 11 muscles participated in this response, with an average capillary participation of 56%. In terms of these microvascular data, the present study demonstrate for the first time ever (1) an appreciable spatial heterogeneity of responses within the capillary network in a single muscle following all three types of occlusions, and (2) a progressively larger muscle-to-muscle heterogeneity of responses with longer duration of occlusion. Since the spatial heterogeneity (i.e. increase, no change or even decrease in flow) was associated with groups of similarly behaving capillaries supplied by a common arteriole, the existence of a flow-suppressing arteriolar mechanism (in addition to metabolic and myogenic vasodilating mechanisms) is postulated to explain the dramatic heterogeneity of response to ischemia in this muscle.

Animals↗
PubMed2000

Hydrogen peroxide decelerates recovery of action potential after high-frequency fatigue in skeletal muscle.

Effects of reactive oxygen species (ROS), especially hydrogen peroxide (H(2)O(2)), on recovery of action potential by resting for 30 min after high-frequency fatigue were studied using frog skeletal muscle fibers. After stimulation at a frequency of 50 HZ for 2 min, the action potential amplitude was decreased by 14.5 mV from controls, and resting membrane was depolarized by 15.4 mV. Action potential duration was also prolonged by high-frequency stimulation (1.5 ms in controls to 2.6 ms). The high-frequency stimulation used here caused no muscle damage. The action potential was partially improved after a 30-min rest. Addition of catalase at 500 units/ml or H(2)O(2) at 0.5 mM to sartorius muscle did not alter any of the parameters of the action potential after high-frequency stimulation. Treatment with catalase accelerated post-fatigue recovery of the action potential. Application of H(2)O(2) delayed post-fatigue recovery of resting and action potentials. When added to detubulated toe muscle fibers, catalase no longer improved the attenuation of action potential induced by high-frequency stimulation, even after a 30-min rest. These findings suggest that removal of H(2)O(2) from transverse tubules is effective for post-fatigue recovery of action potential in skeletal muscle.

Action Potentials↗
PubMed1991

Activation of ATP-sensitive K channels by a K channel opener (SR 44866) and the effect upon electrical and mechanical activity of frog skeletal muscle.

To examine the effects of the activation of adenosine 5'-triphosphate (ATP)-sensitive K channels in a skeletal muscle we have applied the ATP-sensitive K channel opener SR44866 whilst recording single ion channels, voltage-clamped membrane currents, evoked action potentials and tension in sartorius muscles of the frog. In excised inside-out membrane patches SR44866 opened channels which could be inhibited by internal ATP and glibenclamide. In voltage-clamped individual muscle fibres SR44866 evoked a glibenclamide-sensitive membrane current which reversed at -70 mV. The effect of SR44866 was dose dependent with an effective concentration for 50% maximal effect (EC50) of 67 microM and a slope factor of 2. SR44866 dose dependently reduced the duration of the spike after-potential, spike overshoot, Vmax, tetrodotoxin-sensitive voltage-gated inward membrane currents and muscle twitch tension. From this evidence it can be concluded that the opening of ATP-sensitive K channels may be associated with the inhibition of contraction of skeletal muscle.

Action Potentials↗
PubMed1994

The effect of glibenclamide on frog skeletal muscle: evidence for K+ATP channel activation during fatigue.

1. The purpose of this study was to determine whether ATP-sensitive K+ (K+ATP) channels are activated and contribute to the decrease in force during fatigue development in the sartorius muscle of the frog, Rana pipiens. Tetanic force (elicited by field stimulation), action potential and membrane conductance (using conventional microelectrodes), were measured in the presence and absence of glibenclamide, a K+ATP channel antagonist. Experiments were performed in bicarbonate-buffered solutions at pH 7.2. 2. In unfatigued muscle 100 mumol l-1 glibenclamide had no effect on the resting potential, the overshoot, the half-depolarization time or the maximum rate of depolarization of action potentials, while the mean half-repolarization time increased by 19 +/- 4% (+/- S.E.M.) and the maximum rate of repolarization decreased by 17 +/- 5%. 3. Fatigue was elicited using 100 ms tetanic contractions every 1 s for 3 min. In the absence of glibenclamide the mean half-repolarization time increased from 0.57 +/- 0.05 to 0.89 +/- 0.05 ms during fatigue. The mean half-repolarization times after fatigue, when muscle fibres were exposed to 100 mumol l-1 glibenclamide either 60 min prior to fatigue or 60 s before the end of fatigue, were 1.16 +/- 0.08 and 1.17 +/- 0.07 ms respectively. Application of 100 mumol l-1 glibenclamide after 5 min of recovery did not increase the half-repolarization time, but decreased the rate of recovery compared to control values. 4. In unfatigued muscles, 100 mumol l-1 glibenclamide did not affect the tetanic contraction. In the absence of glibenclamide, the mean tetanic force after fatigue was 11.0 +/- 0.9% of prefatigue values. Application of 100 mumol l-1 glibenclamide 60 min before fatigue increased the rate of fatigue development as the mean tetanic force was 4.8 +/- 0.8% after 3 min of stimulation. The addition of 100 mumol l-1 glibenclamide 60 s before the end of fatigue had no effect on tetanic force during this time compared to control. 5. In the absence of glibenclamide, muscles recovered 90.1 +/- 1.6% of their tetanic force after 100 min. Addition of 100 mumol l-1 glibenclamide 60 min prior to fatigue significantly reduced the capacity of muscles to recover their tetanic force: after 100 min of recovery tetanic force was only 47.3 +/- 9.4% of the pre-fatigue value.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1982

Intracellular pH mediates action of insulin on glycolysis in frog skeletal muscle.

In a glucose-free bicarbonate Ringer (5% CO2 in N2), insulin increased intracellular pH (pHi), as determined by [14C]dimethadione, by 0.12 +/- 0.02 and stimulated glycolysis, as monitored by anaerobic lactate production, by 42.9 +/- 3.5% in paired frog sartorius muscles. The effect of insulin on glycolysis was shown to vary approximately linearly with log [Na+]0, being converted in 0.12 mM Na+ Ringer to a 51.5 +/- 8.4% inhibition of glycolysis. As the Na+ free-energy gradient was varied by decreasing [Na+]0 from 104 to 6.8 mM, the changes in glycolytic flux produced by insulin consistently paralleled the changes in pHi produced by the hormone. The relationship between the change in pHi and percent change in glycolytic flux was the same regardless of whether the effects were produced by insulin or by changing CO2. When glycolysis was either stimulated or inhibited, intracellular levels of fructose 6-phosphate varied inversely with glycolytic flux. This indicates that the effect on glycolysis of either insulin or changes in CO2 is due to a change in the activity of phosphofructokinase. The results support the model that the acute effect of insulin on glycolysis is mediated by a change in pHi, consequent to activation by insulin of Na:H exchange at the plasma membrane.

Animals↗
PubMed1993

Antagonism of vasoconstriction by muscle contraction differs with alpha-adrenergic subtype.

It has been suggested that muscle contraction causes prejunctional inhibition of transmitter release from sympathetic nerves. In accordance with this, we found that second-order (50 microns ID) arterioles of the cat sartorius muscle dilate 40-80% more with muscle contraction during 2-, 4-, or 8-Hz sympathetic nerve stimulation than during equivalent constriction produced by intravenous norepinephrine injection. However, when constriction was to the selective alpha 1-agonist phenylephrine, the magnitude of dilation induced by muscle contraction was similar to that seen with sympathetic nerve stimulation, suggesting that prejunctional inhibition is not involved. Alternatively, different receptor subtypes may be activated by sympathetic nerve stimulation and exogenous norepinephrine. In support of this explanation, we found that approximately 50% of the vasoconstrictor effect of sympathetic nerve stimulation (8 Hz) was blocked by prazosin, an alpha 1-adrenergic antagonist, but no further diminution of tone was seen with addiction of yohimbine, an alpha 2-adrenergic antagonist. In contrast, the vasoconstrictor response to exogenous norepinephrine was not affected by prazosin, while addition of yohimbine almost completely blocked the response. These findings suggest that muscle contraction selectively attenuates vasoconstriction mediated by junctional receptors in second-order arterioles.

Animals↗
PubMedDate not supplied

The effect of general anesthetic agents, ouabain, and aldosterone on striated muscle contraction in toad.

Na+ and K+ transport, resting potentials, action potentials, and muscle contraction are interrelated in the excitation-contraction coupling process. Since anesthetics affect the electrogenic Na+ transport mechanism in the toad bladder model and the coupled Na+, K+ transport in muscle, the authors tested the hypothesis that the effects of inhalation anesthetics on ion transport and muscle contraction are parallel. In this study, the effects were assessed of 4 inhalation anesthetics and, for comparison, the effects of ouabain and aldosterone, on contractions of toad sartorius muscle. Cyclopropane, N2O, ether, and halothane, as well as ouabain and aldosterone, increased twitch height in low concentrations. Halothane, ether, and ouabain decreased twitch height in high concentrations. The effect of cyclopropane and N2O, oubain, and aldosterone on muscle contraction closely paralleled their action on electrogenic Na+ transport. This observation supports the hypothesis that the influence of these agents on muscle contraction is linked to the effect on active ion transport or that both effects are equally sensitive to anesthetic agents.

Aldosterone↗
PubMed2006

["Retro-sartorius bypass" an alternative method during graft infection due to gunshot wound: a case report].

Graft infections can be seen after the peripheric vascular operations using synthetic graft. The patient who had femoro-femoral bypass with synthetic graft after a gunshot wound admitted to our department with graft infection and wide tissue loss. The distal pedal pulses were palpable. At the fifth day, the patient had a bleeding on the graft site and underwent emergency operation. Firstly the infected graft material was excised. Then the proximal end of the PTFE graft anastomosed to the external iliac artery with the lomber incision. A tunnel was formed just medial to the superior crista iliaca and under the inguinal ligament. The PTFE graft was passed through this tunnel excluding the infected area behind sartorius muscle and anastomosed to superficial femoral artery. Control angiography revealed that anastomoses were patent. At the graft infections which are especially with wide tissue loss, the retro-sartorius bypass surgery can be performed successfully as an alternative procedure.

Adult↗
PubMed1996

The pattern of stimulation influences the amount of oscillatory work done by frog muscle.

1. A doublet is the interjection of an additional action potential at the beginning of a regular motoneuron discharge pattern. The present experiments were designed to estimate the magnitude of the effect of doublets on the capacity of isolated frog sartorius muscle to do work during oscillatory length changes. 2. For the work loop method, the muscle was subjected to sinusoidal length changes at 4 Hz. Work was calculated from the loop formed when force was plotted against length. Work done was positive when the muscle was shortening and was negative when the muscle was lengthening; net work was the difference. 3. Adding pulses at the start of the stimulus pulse train increased isometric force and markedly increased net work per cycle. Adding one pulse increased the net work by about 52%, but increased isometric force by only 24%. 4. Eighty per cent of the maximum net work was achieved by adding only three pulses at the start of a low-frequency pulse train, i.e. 80% of the work achieved with seventeen pulses could be achieved with only six pulses. 5. The maximum net work per stimulus pulse was achieved with a stimulus train that consisted of five pulses with two being additional initial pulses at 5 ms interpulse intervals, i.e. a triplet. 6. The results of the present study imply that doublet stimulation patterns may be important to reduce the fatigue that occurs during artificial neuromuscular stimulation of skeletal muscle.

Action Potentials↗
PubMed1984

Muscle crossbridge positions from equatorial diffraction data: an approach towards solving the phase problem.

Following a discussion of the problems involved in the analysis of X-ray diffraction data from muscle, a description is given of a possible procedure for solving the phase problem in the case of equatorial diffraction data. The approach involves the use of the Patterson Function which can be determined unambiguously from the observed diffracted intensities. The method is tested using five different muscle-like model density distributions for which the correct phases can be calculated directly. It is then applied to the equatorial X-ray diffraction data from relaxed frog sartorius muscle where it selects a phase set which is also the most likely to be correct on the basis of other available data on frog muscle. This phase set gives rise to a Fourier synthesis map in which the crossbridges form a uniform shelf of density around the myosin filament backbones. Possible lateral movements of the crossbridges from this relaxed configuration in active and rigor muscle are discussed. The approach to solving the phase problem is now being applied to data from fish muscle, insect flight muscle and crab muscle. It should also have its application to other fibrous materials apart from muscle.

Animals↗
PubMed2003

[Unilateral apophyseal fracture of the superior anterior iliac crest--a case report].

While soccer playing a 19 year old man suffered from acute onset of severe pain in the anterior part of the iliac crest. A CT-scan confirmed the unilateral avulsion of the anterior superior iliac spine. Due to only minimal fragment dislocation and still open apophysis we decided to treat this injury conservatively with crutches and partial weight bearing. There were no complications and already three weeks after the accident the young man was nearly painfree. Avulsion of the anterior superior iliac spine most commonly occur in adolescents. The fracture is often missed and treated as muscle injury or hip pain and therefore received a symptomatical therapy. Later a typical hypertrophic callus formation confirms the avulsion fracture. The avulsion occurs by sudden pull of the sartorius muscle to the anterior superior iliac spine. The pull of the muscle dislocates the loose fragment caudally. In most of the cases a conservative treatment is successful.

Adult↗
PubMed1985

Activity of spindle afferents from cat anterior thigh muscles. III. Effects of external stimuli.

Chronically implanted electrodes were used to record the activity of identified single muscle spindle afferents in awake cats during responses to various types of manual and electrical stimulation. During vigorous cyclical responses such as shaking and scratching, spindle afferents generally maintained at least some activity during both lengthening and shortening of the parent muscle, indicating that the programs for these movements include both extra- and intrafusal recruitment. During noncyclical responses such as ipsilateral limb withdrawal and crossed-extension, spindle activity was modest and poorly correlated with extrafusal activity. Weak cutaneous nerve shocks during walking elicited complex excitatory and inhibitory phase-dependent reflexes in the various muscles studied but caused relatively little change in spindle afferent activity, indicating a lack of correlation between alpha and gamma motoneuron activity. A primary and a secondary afferent from sartorius muscle were recorded simultaneously during walking cycles that were perturbed by electrically induced twitches of the antagonist hamstring muscles; both demonstrated highly sensitive, short latency responses to the resulting skeletal motion, consistent with their previously suggested roles in detecting small brief mechanical perturbations. The degree to which fusimotor responses were correlated with extrafusal responses to somatosensory perturbations was highly dependent on the specific nature of the stimulus and the response. Fusimotor reprogramming of the spindle sensitivity appears to be a feature of cyclical movements that are presumably under proprioceptive control, whereas brief perturbations within the context of a particular motor program may be ignored by the fusimotor system.

Afferent Pathways↗
PubMed1981

Changes in the satellite cell population during postnatal growth of pig skeletal muscle.

Changes in the proportion and approximate number of muscle satellite cells were studied by electron microscopy from 1 to 64 weeks of age in the pig. Transverse sections of the white portion of the peroneus longus and sartorius muscles were examined in gilts at 1, 2, 4, 8, 16, 32 and 64 weeks of age. The percentage of fibers that contained myonuclei increased with age, while the percentage of nuclei within the basal lamina that were satellite cell nuclei gradually decreased with age. It was concluded that the ultrastructural characteristics and postnatal changes in the satellite cell population of pig skeletal muscle support previous reports for other mammalian species. However, preliminary evidence suggested that the absolute number of satellite cells increased for some time between 1 and 32 weeks of age in the areas sampled in these two muscles.

Animals↗
PubMed1986

Structural changes during contraction in vertebrate skeletal muscle as studied by time-resolved X-ray diffraction technique.

To obtain information about the structural changes in vertebrate skeletal muscle during contraction, time-resolved X-ray diffraction studies were performed on the intensity changes of the 59 A and 51 A actin layer lines from bullfrog sartorius muscle during the isometric force development, and the intensity changes of the 143 A and 215 A myosin meridional reflections and of the 1.0 and 1.1 equatorial reflections when isometrically contracting muscle was subjected to sinusoidal length changes (1%, 5-10 Hz) with the following results. The integrated intensities of the 59 A and 51 A actin layer lines increased during the force development by 30-50% for the 59 A reflection, and by about 70% for the 51 A reflection compared to their respective resting values. These intensity changes were greater than those taking place during the transition from rest to rigor state, and observed to precede the intensity changes of the 429 A myosin off-meridional reflection and of equatorial reflections. When sinusoidal length changes were applied to the muscle generating steady isometric force, the resulting periodic intensity changes in the 1.0 and 1.1 equatorial reflections were in phase and in antiphase with the length changes respectively. On the other hand, the 143 A myosin reflection exhibited a characteristic periodic changes; its intensity reached a maximum at each boundary between the stretch and release phases of the length changes. These results are discussed in connection with the behaviour of the cross-bridges during contraction.

Actin Cytoskeleton↗
PubMed1968

Actions of some anions on electrical properties and mechanical threshold of frog twitch muscle.

1. Using two micro-electrodes in a point-voltage clamp technique, the effects of the lyotropic anions, NO(3) (-), Br(-), I(-), SCN(-), and CH(3)SO(4) (-), and of SO(4) (2-) on the mechanical threshold and electrical properties of frog sartorius muscle were studied.2. In chloride Ringer solution the spike threshold was -59 mV, mechanical threshold -48 mV, and the threshold for delayed rectification of the total current at about 100 msec -52 mV.3. When Cl(-) was replaced by one of the lyotropic anions, the effective resistance determined at -100 mV tended to increase. But, because of the variability of the effective resistance in individual fibres, most lyotropic anions did not cause a statistically significant increase in the effective resistance. Only I(-) and SO(4) (2-) significantly increased the effective resistance.4. Most lyotropic anions had no significant effect on the spike threshold; I(-), at 58 mM, lowered it slightly. Sulphate raised the threshold.5. Tetrodotoxin (0.1 mug/ml.) abolished the spikes, but did not affect the mechanical and delayed rectification thresholds. It was, therefore, used to pre-treat all preparations for determining these thresholds.6. All lyotropic anions lowered the mechanical and the delayed rectification thresholds, the order of effectiveness being approximately SCN(-) > I(-) > NO(3) (-) > CH(3)SO(4) (-) > Br(-). As in Cl(-) Ringer, the two thresholds lay very close together in every case. Sulphate raised slightly both the mechanical and delayed rectification thresholds, again in close parallel.7. This close agreement of the mechanical and delayed rectification thresholds is not caused by movement artifact, because in fibres in which visible contractions were eliminated with hypertonic solutions the delayed rectification thresholds were the same as those in contracting fibres.8. In spite of the close agreement, reasons are given to doubt a direct causal relationship between the mechanical and delayed rectification thresholds.9. Nitrate apparently had little effect on the rate of inactivation of the outward current, or on the relation between steady-state inactivation and membrane potential.

Animals↗
PubMedDate not supplied

Entrapment neuropathy of the infrapatellar branch of the saphenous nerve.

This paper describes a syndrome of entrapment of the infrapatellar branch of the saphenous nerve attributable to its anatomical relationship to the sartorius muscle and justifies its identification as a distinct entity. Surgery was performed on four knees in three patients for localized pain and tenderness. The infrapatellar nerve was found entrapped behind the sartorius tendon against the prominent edge of the medial femoral condyle and sharply angulated while passing around the sartorius in two knees. Entrapment during passage of the nerve through a slit in the musculotendinous portion of the sartorius was observed in the others. All patients had complete relief of symptoms after translocation of the nerve away from the site of entrapment. The characteristic findings demonstrate the need to be aware of the possibility of entrapment of the infrapatellar branch of the saphenous nerve when evaluating patients with pain on the medial aspect of the knee.

Adult↗
PubMed1981

Ultrastructural analysis of skeletal muscle development in the fetal pig.

Myogenesis was investigated at the ultrastructural level in the fetal pig at 35, 52, 65, 80, 95 and 110 days of gestation. At each stage of gestation, the predominant type II fiber type portion of the peroneus longus and sartorius muscles was examined. The sequence of events for normal myogenesis in the pig was generally similar to that reported for the skeletal muscle of other vertebrate species. In addition, the time interval for sequential development of myogenesis was similar between the two muscles. Centrioles were identified in primary fetal fibers and also in secondary fibers. No morphological evidence of mitotic activity was found in the myonuclei. The organization of myofibers into fasciculi was unrelated both temporally and spatially to capillary and neural development.

Animals↗
PubMed1992

Effects of dantrolene on myoplasmic free [Ca2+] measured in vivo in patients susceptible to malignant hyperthermia.

Malignant hyperthermia (MH) is a genetic disease characterized by hypermetabolism in skeletal muscle following a triggering stimulus and can be reversed or pretreated with dantrolene sodium. The myoplasmic free [Ca2+] was measured, using Ca2+ selective microelectrodes in vivo in the superficial fibers of the sartorius muscle of eight MH-susceptible and eight control subjects. Both groups received continuous epidural anesthesia with chloroprocaine 3%. In both the control and MH muscle fibers, the myoplasmic free [Ca2+] was measured before and after the intravenous administration of a cumulative dantrolene dose of 0.5, 1.5, and 2.5 mg/kg. The mean resting myoplasmic free [Ca2+] was 0.112 +/- 0.004 microM (mean +/- SEM n = 32) in the control and 0.485 +/- 0.022 microM (n = 33) in the MH subjects. In the MH subjects, dantrolene induced a dose-dependent reduction in myoplasmic free [Ca2+]. The 0.5-mg/kg dose reduced it to 0.326 +/- 0.017 microM (n = 22), the 1.5-mg/kg dose to 0.233 +/- 0.015 microM (n = 25), and the 2.5-mg/kg dose to 0.092 +/- 0.008 microM (n = 26). In controls, dantrolene also reduced resting myoplasmic free [Ca2+] but to a lesser extent. The 0.5-mg/kg dose reduced it to 0.096 +/- 0.004 microM (n = 22), the 1.5-mg/kg dose to 0.077 +/- 0.003 microM (n = 23), and the 2.5-mg/kg dose to 0.068 +/- 0.002 microM (n = 27). The results of the study extend our previous findings in humans and swine and demonstrate that it is possible to measure myoplasmic free [Ca2+] in vivo in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗