Sieving of electrolytes at capillary wall of cat skeletal muscle by osmotic water flow

1993 ◽  
Vol 265 (6) ◽  
pp. H1869-H1874 ◽  
Author(s):  
P. D. Watson
Keyword(s):  
Skeletal Muscle ◽  
Water Flow ◽  
Water Movement ◽  
Significant Proportion ◽  
Free Water ◽  
Mammalian Skeletal Muscle ◽  
Sodium Potassium ◽  
Osmotic Water ◽  
Significant Difference ◽  
Plasma Electrolytes

To test the hypothesis that a significant proportion of transcapillary water flow occurs through solute-restricting channels, we investigated the effects of transcapillary water movement on plasma electrolytes in isolated perfused cat skeletal muscle. The lower hindlimbs of anesthetized cats were perfused with a plasma-albumin solution and were weighed to determine transcapillary water movement. Osmolality was increased 60–70 mosmol/kgH2O with sucrose, creating water fluxes of 8–10 ml.min-1.100 g-1, and the changes in the venous concentrations of sodium, potassium, and chloride were determined. The ion concentrations were all reduced by 6–7% with no significant difference between them. The amount of reduction was quantitatively explained by the flow of ion-free water from the interstitial space into plasma and the diffusion of electrolyte in the same direction. These findings support the hypothesis that important water-only transcapillary channels exist in mammalian skeletal muscle. The observations may also explain some of the electrolyte changes seen in intense exercise.

An integrative, in situ approach to examining K+ flux in resting skeletal muscle

2001 ◽  
Vol 79 (12) ◽  
pp. 996-1006 ◽  
Author(s):  
Michael I Lindinger ◽  
Thomas J Hawke ◽  
Lisa Vickery ◽  
Laurie Bradford ◽  
Shonda L Lipskie
Keyword(s):  
Skeletal Muscle ◽  
Drug Effects ◽  
Potassium Transport ◽  
Mammalian Skeletal Muscle ◽  
Minimal Effect ◽  
Bovine Erythrocyte ◽  
Perfusion Medium ◽  
Sodium Potassium ◽  
Unidirectional Flux

The contributions of Na+/K+-ATPase, K+ channels, and the NaK2Cl cotransporter (NKCC) to total and unidirectional K+ flux were determined in mammalian skeletal muscle at rest. Rat hindlimbs were perfused in situ via the femoral artery with a bovine erythrocyte perfusion medium that contained either 86Rb or 42K, or both simultaneously, to determine differences in ability to trace unidirectional K+ flux in the absence and presence of K+-flux inhibitors. In most experiments, the unidirectional flux of K+ into skeletal muscle (JinK) measured using 86Rb was 8–10% lower than JinK measured using 42K. Ouabain (5 mM) was used to inhibit Na+/K+-ATPase activity, 0.06 mM bumetanide to inhibit NKCC activity, 1 mM tetracaine or 0.5 mM barium to block K+ channels, and 0.05 mM glybenclamide (GLY) to block ATP-sensitive K+ (KATP) channels. In controls, JinK remained unchanged at 0.31 ± 0.03 µmol·g–1·min–1 during 55 min of perfusion. The ouabain-sensitive Na+/K+-ATPase contributed to 50 ± 2% of basal JinK, K+ channels to 47 ± 2%, and the NKCC to 12 ± 1%. GLY had minimal effect on JinK, and both GLY and barium inhibited unidirectional efflux of K+ (JoutK) from the cell through K+ channels. Combined ouabain and tetracaine reduced JinK by 55 ± 2%, while the combination of ouabain, tetracaine, and bumetanide reduced JinK by 67 ± 2%, suggesting that other K+-flux pathways may be recruited because the combined drug effects on inhibiting JinK were not additive. The main conclusions are that the NKCC accounted for about 12% of JinK, and that KATP channels accounted for nearly all of the JoutK, in resting skeletal muscle in situ.Key words: sodium potassium chloride cotransporter, NKCC, Na+/K+-ATPase, potassium channels, potassium transport, in situ rat hindlimb.

Hypothermia: alterations in cardiac and skeletal muscle electrolytes

1959 ◽  
Vol 196 (4) ◽  
pp. 706-708 ◽  
Author(s):  
W. Robert Beavers ◽  
J. T. Rogers
Keyword(s):  
Skeletal Muscle ◽  
Potassium Chloride ◽  
Cardiac Muscle ◽  
Normal Values ◽  
Intracellular Water ◽  
Sodium Potassium ◽  
Hypertonic Glucose ◽  
Plasma Electrolytes ◽  
Made In

Analyses of sodium, potassium, chloride and water of cardiac and skeletal muscle were made in normal dogs, in animals cooled to rectal temperatures of 20°C, and in cooled animals receiving 25% glucose intravenously. Using these data and determinations of plasma electrolytes, muscle intracellular water was calculated. An increase in cardiac muscle potassium and in calculated intracellular water of both cardiac and skeletal muscle was noted in the cooled animals. Administering hypertonic glucose during cooling increased cardiac muscle potassium to even higher levels and calculated intracellular water of cardiac and skeletal muscle was similar to normal values.

Activation energy for water transport in toad bladder

1983 ◽  
Vol 244 (1) ◽  
pp. C44-C49 ◽  
Author(s):  
P. Eggena
Keyword(s):  
Membrane Permeability ◽  
Water Flow ◽  
Room Temperature ◽  
Water Movement ◽  
Bladder Wall ◽  
Close Correlation ◽  
Bulk Water ◽  
Bulk Solution ◽  
Osmotic Water ◽  
Osmotic Water Flow

Activation energies (Ea) for water movement across vasopressin-(ADH) sensitive epithelia have been reported to be about 10 kcal/mol (1, 12). The present study shows that measurements of Ea for osmotic water flow across toad bladders are unreliable, because a temperature change induces marked alterations in membrane permeability to water within a 2.5-min interval. Thus bladders equilibrated with ADH either at room temperature or at 33 degrees C and then suddenly subjected to a lower temperature were found to exhibit a marked increase in membrane permeability to water. This observation suggests that there is a rapid turn-over of water permeability sites and that sudden exposure to cold inhibits the removal more than the induction of sites by ADH. To stabilize ADH-induced water channels for Ea measurements, bladders were exposed to ADH at room temperature, fixed with glutaraldehyde, and subjected to osmotic gradients at different temperatures. The Ea values for osmotic water flow across these ADH-permeabilized, glutaraldehyde-fixed bladders were 5.1 (4-12 degrees C), 4.3 (12-21 degrees C), 3.6 (21-36 degrees C), and 3.6 kcal/mol (30-38 degrees C). Ea values for shear viscosity of water in these temperature ranges were calculated to be 4.7, 4.2, 4.1, and 3.6 kcal/mol, respectively. The close correlation between Ea values for bulk water viscosity and osmotic water flow across the bladder wall suggests that an equivalent number of hydrogen bonds must be broken to achieve an increase in water flow through ADH-induced channels and an increase in fluidity of water in bulk solution.

A Method of Estimating the Relative Volumes of Water Flowing Over the Different Gills of a Freshwater Fish

1968 ◽  
Vol 48 (3) ◽  
pp. 533-544
Author(s):  
J. E. PALING
Keyword(s):  
Freshwater Fish ◽  
Water Flow ◽  
Brown Trout ◽  
Water Movement ◽  
The Other ◽  
Total Water ◽  
Vigorous Exercise ◽  
Significant Difference ◽  
Current Flows

1. A technique is described which uses marker parasites to estimate the relative volumes of water flowing over the different gills of a freshwater fish. 2. It was found that in brown trout from Windermere most of the respiratory current flows over the second and third pairs of gills, less flows over the first pair on each side and least of all across the most posterior pairs of gill. Similarly, the median pair of gill slits carries more of the respiratory current than any of the other slits whereas first and fifth pairs of gill slits together carry only about one-sixth of the total water flow. 3. Hatchery-bred brown trout showed a slight but significant difference in pattern of water movement over their gills following vigorous exercise. Possible reasons for this are discussed.

scholarly journals PO-064 A potential role of stretch-activated channels in anabolic mechanotransduction in the atrophied rat soleus muscle

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
Timur Mirzoev ◽  
Sergey Tyganov ◽  
Boris Shenkman
Keyword(s):  
Skeletal Muscle ◽  
Soleus Muscle ◽  
Contractile Function ◽  
Mammalian Skeletal Muscle ◽  
Mechanical Unloading ◽  
Mtorc1 Signaling ◽  
Significant Difference ◽  
Rat Soleus Muscle ◽  
Isolated Rat

Objective Prolonged immobilization or unloading of skeletal muscle causes muscle disuse atrophy, which is characterized by a reduction in muscle cross-sectional area and compromised contractile function. To date, the mechanisms of anabolic mechanotransduction in the atrophied mammalian skeletal muscle remain poorly understood. The aim of the present study was to assess a possible role of stretch-activated ion channels (SAC) in the propagation of a mechanical signal to anabolic signaling and protein synthesis (PS) in an isolated rat soleus muscle following mechanical unloading. Methods The mechanical unloading was performed via hindlimb suspension (HS). Twenty-eight male Wistar rats weighing were randomly assigned to the following 4 groups (n=7/group): 1) vivarium control (C), 2) control + SAC inhibitor (gadolinium) (C+Gd3+), 3) 7-day HS (HS), 4) 7-day HS + SAC inhibitor (HS+Gd3+). Following unloading, an isolated rat soleus was placed in an organ culture medium and subjected to a bout of eccentric contractions (EC). Upon completion of the EC, muscles were collected for Western blot analyses to determine the content of the key anabolic markers. The rate of PS was measured by SUnSET technique. Results EC-induced increase in PS was significantly less in the HS and HS+ Gd3+ groups vs. the C group. There was no statistically significant difference between the HS and HS+ Gd3+ groups in terms of EC-induced increase in muscle PS. A decrease in EC-induced phosphorylation of p70S6K, 4E-BP1, RPS6 and GSK-3beta in the 7-day unloaded soleus treated with SAC inhibitor did not differ from that of the 7-day unloaded soleus without SAC blockade. Thus, the inhibition of SAC with gadolinium did not lead to further decline in EC-induced phosphorylation of the key anabolic markers and muscle PS. Conclusions The results of the study suggest that attenuation of mTORC1-signaling and PS in response to EC in unloaded soleus muscle may be associated with inactivation of SAC. The study was supported by the RFBR grant # 16-34-60055.

scholarly journals Myogenic Response to Increasing Concentrations of Ammonia Differs between Mammalian, Avian, and Fish Species: Cell Differentiation and Genetic Study

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 840
Author(s):  
Emily Miramontes ◽  
Bartosz Kempisty ◽  
James Petitte ◽  
Srinivasan Dasarathy ◽  
Magdalena Kulus ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Untreated Control ◽  
Sodium Acetate ◽  
Ammonium Acetate ◽  
Negative Regulator ◽  
C2c12 Cells ◽  
Myogenic Response ◽  
Mammalian Skeletal Muscle ◽  
Significant Difference ◽  
Myoblast Cells

Ammonia is very toxic to the body and has detrimental effects on many different organ systems. Using cultured myoblast cells, we examined ammonia’s effect on myostatin expression, a negative regulator of skeletal muscle growth, and myotube diameters. The objective of this study was to examine how murine, avian, and fish cells respond to increasing levels of ammonia up to 50 mM. The murine myoblast cell line (C2C12), primary chick, and primary tilapia myoblast cells were cultured and then exposed to 10, 25, and 50 mM ammonium acetate, sodium acetate, and an untreated control for 24 h. High levels of ammonia were detrimental to the C2C12 cells, causing increased Myostatin (MSTN) expression and decreased myotube diameters between 10 and 25 mM (p < 0.002). Ammonia at 10 mM continued the positive myogenic response in the chick, with lower MSTN expression than the C2C12 cells and larger myotube diameters, but the myotube diameter at 50 mM ammonium acetate was significantly smaller than those at 10 and 25 mM (p < 0.001). However, chick myotubes at 50 mM were still significantly larger than the sodium acetate-treated and untreated control (p < 0.001). The tilapia cells showed no significant difference in MSTN expression or myotube diameter in response to increasing the concentrations of ammonia. Overall, these results confirm that increasing concentrations of ammonia are detrimental to mammalian skeletal muscle, while chick cells responded positively at lower levels but began to exhibit a negative response at higher levels, as the tilapia experienced no detrimental effects. The differences in ammonia metabolism strategies between fish, avian, and mammalian species could potentially contribute to the differences between species in response to high levels of ammonia. Understanding how ammonia affects skeletal muscle is important for the treatment of muscle wasting observed in liver failure patients.

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