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PubMed1963

CHANGES IN THE MEMBRANE PERMEABILITY OF FROG'S SARTORIUS MUSCLE FIBERS IN CA-FREE EDTA SOLUTION.

The changes in the membrane permeability to sodium, potassium, and chloride ions as well as the changes in the intracellular concentration of these ions were studied on frog sartorius muscles in Ca-free EDTA solution. It was found that the rate constants for potassium and chloride efflux became almost constant within 10 minutes in the absence of external calcium ions, that for potassium increasing to 1.5 to 2 times normal and that for chloride decreasing about one-half. The sodium influx in Ca-free EDTA solution, between 30 and 40 minutes, was about 4 times that in Ringer's solution. The intracellular sodium and potassium contents did not change appreciably but the intracellular chloride content had increased to about 4 times normal after 40 minutes. By applying the constant field theory to these results, it was concluded that (a) P(Cl) did not change appreciably whereas P(K) decreased to a level that, in the interval between 10 and 40 minutes, was about one-half normal, (b) P(Na) increased until between 30 and 40 minutes it was about 8 times normal. The low value of the membrane potential between 30 and 40 minutes was explained in terms of the changes in the membrane permeability and the intracellular ion concentrations. The mechanism for membrane depolarization in this solution was briefly discussed.

Animals↗
PubMed1978

Diffusion and consumption of oxygen in the resting frog sartorius muscle.

Adaptations of the method of Takahashi et al. (1966. J. Gen. Physiol. 50:317-333) were used to test the validity of the one-dimensional diffusion equation for O2 in the resting excised frog sartorius muscle. This equation is: (formula: see text) where x is the distance perpendicular to the muscle surface. t is time, P(x, t) is the partial pressure of O2,D and alpha are the diffusion coefficient and solubility for O2 in the tissue, and Q is the rate of O2 consumption. P(O, t), the time-course of PO2 at one muscle surface, was measured by a micro-oxygen electrode. Transients in the PO2 profile of the muscle were induced by two methods: (a) after an equilibration period, one surface was sealed off by a disc in which the O2 electrode was embedded; (b) when PO2 at this surface reached a steady state, a step change was made in the PO2 at the other surface. With either method, the agreement between the measured P(O, t) and that predicted by the diffusion equation was excellent, making possible the calculation of D and Q. These two methods yielded statistically indistinguishable results, with the following pooled means (+/- SEM): (formula: see text) At each temperature, D was independent of muscle thickness (range, 0.67-1.34 mm). The activation energy (EA) for diffusion of oxygen in muscle was -3.85 kcal/mol, which closely matches the corresponding value in water. Together with absolute values of D in water taken from the literature, the present data imply that (Dmuscle/DH2O) is in the range 0.59-0.69. This value, and that of EA, are in agreement with the theory of Wang (1954, J. Am. Chem. Soc. 76:4755-4763), suggesting that with respects to the diffusion of O2, to a useful approximation, frog skeletal muscle may be considered simply as a homogeneous protein solution.

Animals↗
PubMed1979

The 24Na-transport increasing effect of veratrine in frog sartorius muscle influenced by the tonicity, composition and temperature of the external environment.

The influence of tonicity, ionic composition and temperature of the incubating medium on the increasing effect of veratrine on 24Na transport in the frog sartorius muscle has been studied. (1) The effect of veratrine applied during 24Na loading on the rate coefficient for sodium loss depended on the tonicity of the medium. The rate of loss of 24Na from muscles loaded in the presence of veratrine was not affected if the muscles had been equilibrated in hypertonic medium. However, when treating the muscles with veratrine in isotonic medium during 24Na loading, we obtained a twofold increase in the rate coefficient for sodium loss. (2) The effect of veratrine applied during the desaturation period on 24Na efflux was also found to depend on the tonicity of the medium. Veratrine applied during the desaturation period increased the 24Na efflux in muscles equilibrated in isotonic Ringer's solution. However, when the muscles were equilibrated in hypertonic medium, veratrine did not influence 24Na efflux, not even after the rate of 24Na loss had been decreased by ouabain. (3) Hypertonic medium inhibited the Li uptake-enhancing effect of veratrine, while in isotonic medium veratrine had a marked enhancing effect. (4) In hypertonic medium lithium inhibited the otherwise characteristic increasing effect of veratrine on 24 Na uptake. (5) The increase of intracellular sodium concentration as a result of incubation in cold, potassium-free Ringer's solution did not influence the 24Na exchange-increasing effect of veratrine in isotonic medium. (6) The increasing effects of 0.1 and 0.5 mM veratrine on 24Na influx had the same degree at room temperature. However, at 5 degrees C 0.5 mM veratrine increased 24Na influx to a greater extent than 0.1 mM. (7) On the basis of our earlier experiments it has been suggested that the site of action of the 24Na uptake-increasing effect of veratrine could be the neural structures in the muscle equilibrated in hypertonic media. The present experiments confirm this suggestion and at the same time demonstrate that there are substantial differences in the mechanism of the sodium transport of veratrine-treated neural and muscle membranes, which become more apparent in hypertonic medium.

Animals↗
PubMed1975

Simultaneous efflux of K+ and Na+ from frog sartorius muscle freed of extracellular fluids: evidence for rapidly exchanging Na+ from the cells.

After removal of radioactivity trapped in the extracellular space and correcting for the contribution of connective tissue elements, the K+ -efflux curve of frog sartorius muscles becomes a perfect straight line in a semilogarithmic plot. The simultaneously recorded Na+-efflux curve from the same muscles remains strongly curved, and can be resolved into a slow fraction (which conventionally has been regarded as representing the entire cell Na+) and at least one fast fraction. The fast fraction of Na+ could not have originated from a sarcoplasmic reticulum or any other extracellular space extensions; otherwise a similar fast fraction should exist for K+. The data agree with the interpretation that it is the fast fraction that is rate limiting by cell permeability and the slow fraction by desorption from intracellular adsorption sites.

Adsorption↗
PubMed1975

The effect of zinc ions on the gating of the delayed potassium conductance of frog sartorius muscle.

1. A voltage-clamp method was used to examine the effects of zinc ions on the delayed potassium currents and also the slowly activating potassium currents that are turned on by depolarizing the membrane of frog sartorius muscle fibres. 2. In a control solution, the delayed potassium conductance had a maximum value of 17-8 +/- 2-5 mmho.cm-2. The reversal potential for the currents was -76-9 +/- 2-5 mV. The membrane potential where ninfinity had the value 0-5 was -49 mV. 3. The major effect of zinc ions was to slow the delayed potassium currents. The value of taun was increased approximately tenfold in 0-1 mM zinc. Zinc does not alter the effective valency of the gating particles of the potassium channel, but the conductance was shifted to more positive membrane potentials: in 0-1 mM zinc, the membrane potential where ninfinity had the value 0-5 was -32 mV. 4. Zinc ions, at a concentration of 0-1 mM, also reduced the maximum potassium conductance by about 60% to 7-3 +/- 0-8 mmho, cm-2; they did not alter the reversal potential of the currents, which had a value in 0-1 mM zinc of -74-6 +/- 1-5 mV. 5. Zinc ions had little or no effect on the rate of inactivation of the potassium currents. 6. Zinc ions had little effect on the conductance attributable to the slowly activating potassium system. In 0-01 mM zinc this conductance had a value at 0 to +10 mV of 1-25 +/- 0-29 mmho.cm-2. Zinc did not alter the reversal potential of the slow potassium currents from the value of -85 +/- 1-6 mV in the absence of zinc and had no effect on the time course of the turn-off of these currents at -60 mV. 7. The delayed potassium currents obtained in 0-002 and 0-01 mM zinc could not be fitted exactly with a simple fourth order equation, but were well fitted by a model proposing that zinc ions slow the opening and closing of the gating mechanism to one tenth the normal rate when they bind to the gating molecule. If the binding sites are not saturated, those gating molecules that do not bind zinc are assumed to be quite unaltered in their properties, though the potential dependence of their rate constants alphan and betan was assumed to be shifted to more positive levels. In one fibre in 0-01 mM zinc, the model fitted the currents best if 50% of the gating molecules bound zinc.

Animals↗
PubMed1989

Microcirculatory responses in cat sartorius muscle to hemorrhagic hypotension.

The purpose of this study was to examine changes in the microcirculation that might explain the rise in vascular resistance during hemorrhagic hypotension. Diameter and red blood cell velocity of microcirculatory vessels in exteriorized cat sartorius muscles were studied during 4 h of hemorrhagic hypotension at 60 mmHg. During hypotension, vascular resistance of the muscles rose approximately 70% while calculated volume flow in arterioles and venules fell to about the same degree. Average red blood cell velocity for all capillaries showed a comparable decline. Red blood cell flow stopped in approximately 60% of capillaries, but the extent of stoppage varied greatly among capillary fields. Arterioles larger than 45 microns constricted 9-29%, with the largest arterioles showing the greatest constriction. Arterioles smaller than 45 microns dilated 34-56%, with the smallest arterioles showing the greatest dilation. Venular diameter did not change with hemorrhage. The predominance of arteriolar dilation, especially in the later stages of hypotension, should lead to a fall in vascular resistance of the muscle. This effect may be offset by constriction of arteries outside the microcirculatory field observed and blockage of capillaries or venules by formed elements.

Animals↗
PubMed2001

A case of intramuscular sparganosis in the sartorius muscle.

Intramuscular sparganosis is not common, and its rarity makes it difficult to be distinguished from soft tissue tumors. A case of rare intramuscular sparganosis is reported. A 44-year-old man presented with a painful mass in the left thigh for 8 months, which was initially diagnosed a as soft tissue tumor. Ultrasonography and MRI revealed a multilobulated mass in the sartorius muscle. After the needle biopsy under the guidance of ultrasonography, sparganum was discovered under microscopic examination of the excised tissue. Surgical excision was performed, and a live larva of sparganum was removed. Sparganosis should be considered in the differential diagnosis of soft tissue tumors, especially among Koreans who have frequently ingested mountain water and consumed raw snakes or frogs.

Adult↗
PubMed1982

Comparison of physical and biochemical energy balances: chemical breakdown, heat production, and oxygen consumption in frog sartorius muscle.

During the last decade two types of energy balance discrepancies were reported: 1) enthalpy production (heat + work) during contraction is greater than that expected on the basis of the known molar enthalpies and phosphagen breakdown; 2) recovery oxygen consumption is greater than that predicted when using standard biochemical stoichiometry and the phosphagen breakdown during contraction (delta approximately P). To test whether these phenomena were causally related, measurements of delta approximately P, oxygen consumption (Jo2), and enthalpy production during contraction (QI) and recovery (QR) were made on frog sartorius muscle at O C. To achieve equal precision among these diverse measurements, a steady-state protocol involving 3-s isometric tetani at 256-s intervals was employed. delta approximately P during the first 3-s tetanus was not different from that during a contraction in the steady state, and averaged 1.1 mumol/g. Steady-state Jo2 was 0.11 mumol-min-1.g-1, approximately 70% of the maximum rate. QI and QR were 88.2 and 93.3 mJ/g (QR/QI = 1.06). Neither the enthalpy during contraction nor recovery oxygen consumption could be accounted for in terms of delta approximately P. However, a total energy balance was achieved, i.e., the total enthalpy production could be accounted for solely in terms of the measured Jo2 and the molar enthalpy of carbohydrate oxidation. As the oxidation of glycogen is implicated as the only net reaction, the unknown reactions producing the unexplained enthalpy during contraction must be reversed during the recovery period. This reversal would require hydrolysis during recovery of mumol ATP per 35.2 mJ of unexplained enthalpy if the theoretical ADP/O ratio of 3.25 is to be attained. Thus a major portion of the phosphagen breakdown associated with muscle contraction is likely to occur during recovery.

Adenosine Diphosphate↗
PubMed1989

Series elasticity in frog sartorius muscle during release and stretch.

When a stretch is applied to an isolated muscle during tetanic stimulation, the force developed is higher than the maximal isometric tension (Po). This force puts the series elastic component (SEC) under tension and in a domain which is not well defined in terms of tension-extension curve. In the present work, an attempt was made to determine the stiffness of the SEC for tensions greater than Po, using the sartorius muscle of the frog. For this purpose, rapid releases and stretches of different amplitudes were given during maximal isometric contractions. Plotting normalized tension (P/Po) against normalized length changes (negative or positive extensions, delta L/Lo.10(2] produced a tension-extension curve. The slopes of the linear part of each relationship on both sides of Po indicated an increase in SEC stiffness when the muscle was rapidly stretched. Furthermore, the transient character of the increase in stiffness was studied by measuring SEC stiffness during rapid releases applied at various time intervals after stretches: the muscle was found to be stiffer as the time interval was shorter. The results are discussed in terms of (i) non-linear behaviour of the passive and active parts of the SEC, (ii) enhancement of storage and release of potential energy.

Animals↗
PubMed1992

Z-line/I-band and A-band lattices of intact frog sartorius muscle at altered interfilament spacing.

Muscle contraction has long been known to be affected by the osmolarity of the bathing solution. Part of this effect is caused by changes in interfilament spacing in the A-band. We have investigated the variation in spacing of the square lattice of thin filaments within and near the Z-line (the Z-line/I-band or Z-I lattice) in intact frog sartorius muscle over a wide range of osmolarities and compared it with the corresponding changes in the A-band lattice. Both lattices have a lower limit for compression and an upper limit for swelling. The spacing of the Z-I lattice is nearly proportional to that of the A-band, but shows a 2-3% variation at extreme shrinkage or swelling. In normal intact muscle, the osmotically-inactive volume of both lattices is between 20 and 30%. These in vivo measurements of lattice spacing differ significantly from those observed in electron micrographs. With moderate variations in osmolarity, lattice spacing and muscle fibre width show similar behaviour, but at extreme osmolarities, the lattice spacing changes less than the fibre width. An equatorial reflection was observed in intact muscle, previously identified in skinned muscle, which does not index on the A-band and which changes with osmolarity in a manner different from that observed for the A-band and Z-I lattices. This reflection may arise from changes in the ordering of the Z-I lattice or may involve components additional to the thick and thin filaments.

Actin Cytoskeleton↗
PubMedDate not supplied

Distally based sartorius muscle flap in the treatment of infected femoral arterial prostheses.

Although less frequent, arterial prosthetic infections are still a disaster for patient and surgeon since they can lead to multiple complications. The inguinal area is the site of more than three-quarters of the graft infections because of anatomical and technical factors. Of all the proposed forms of treatment none has proven to be totally effective and applicable to all cases. We have employed a technique in which the infected portion of the graft is removed, replaced by a new graft and covered with a distally based sartorius muscle flap. Two illustrative cases are presented in which the procedure proved to be successful for two and for eleven years, and the question is raised as to the benefits of this maneuver in the prevention of infection in those cases that require re-operation.

Aneurysm↗
PubMed1990

Intracellular calcium measurements with PVC-resin Ca-selective microelectrodes in frog proximal tubules and sartorius muscle fibers.

To measure ion activity of intracellular calcium, (Ca)i, we manufactured a Ca2(+)-selective microelectrode based on a neutral carrier, ETH-1001, with or without polyvinylchloride column (PVC-resin). Before and after cell impalements (n = 7), PVC-resin Ca2(+)-selective microelectrodes exhibited Nernstian slopes in the range of p(Ca) from 3 to 7 (the mean slope constant: 29.1 and 29.4 mV/p(Ca), respectively) and sub-Nernstian slopes between p(Ca) = 7 and 8 (21.6 and 21.1 mV/p(Ca]. Individual detection limits of PVC-resin microelectrodes averaged p(Ca) = 8.5 before and 8.3 after cell impalements. In contrast, the non-PVC-resin microelectrode exhibited a poor response between p(Ca) = 7 and 8 especially after cell impalements. Normal values obtained with the PVC-resin microelectrode for (Ca)i of proximal tubule cells and resting sartorius muscle fibers in the bullfrog averaged 18 +/- 2 (n = 10) and 12 +/- 2 (n = 7) nM (mean +/- S.E., number of observations), respectively. We conclude that 1) the PVC-resin microelectrode is a useful tool for measuring intracellular ion activities, and 2) the values of intracellular Ca2+ activity of the proximal tubule and skeletal muscle fibers measured with this microelectrode are in a lower range among the various values reported before with the other methods.

Animals↗
PubMed1994

Effects of 3,4-diaminopyridine on myoplasmic calcium and phosphoinositide hydrolysis in frog sartorius muscle fibers.

Using Ca(2+)-selective microelectrodes, the effects of 3,4-diaminopyridine (DAP) on myoplasmic calcium ([Ca2+]i) were studied in frog satorius muscle fibers. DAP induced an increase of [Ca2+]i in a concentration-dependent manner. DAP 1 mmol.L-1 increased the [Ca2+]i from control 166 +/- 41 nmol.L-1 to 416 +/- 69 nmol.L-1 (n = 10). In the absence of external calcium, DAP still enhanced [Ca2+]i. [Ca2+]i of the fibers bathed in Ca(2+)-free Ringer's solution containing DAP 1 mmol.L-1 was 152 +/- 43 nmol.L-1, which was significantly higher than 77 +/- 35 nmol.L-1 of [Ca2+]i of the fibers in Ca(2+)-free Ringer's solution. In addition, DAP promoted the hydrolysis of phosphoinositides, and DAP-induced hydrolysis was more in the presence of external calcium. It is suggested that, through enhancing the hydrolysis of phosphoinositides, DAP released Ca2+ from intracellular Ca2+ store in frog sartorius muscle fibers.

4-Aminopyridine↗