scholarly journals Effects of External Potassium and Strophanthidin on Sodium Fluxes in Frog Striated Muscle

1965 ◽  
Vol 48 (3) ◽  
pp. 489-514 ◽  
Author(s):  
Paul Horowicz ◽  
Carl J. Gerber
Keyword(s):  
Active Transport ◽  
Striated Muscle ◽  
Transport Processes ◽  
The Other ◽  
Detectable Effect ◽  
Semitendinosus Muscle ◽  
Ion Concentrations ◽  
Na Efflux ◽  
External Potassium ◽  
External K

Unidirectional Na fluxes in isolated fibers from the frog's semitendinosus muscle were measured in the presence of strophanthidin and increased external potassium ion concentrations. Strophanthidin at a concentration of 10-5 M inhibited about 80 per cent of the resting Na efflux without having any detectable effect on the resting Na influx. From this it is concluded that the major portion of the resting Na efflux is caused by active transport processes. External potassium concentrations from 2.5 to 7.5 mM had little effect on resting Na efflux. Above 7.5 mM and up to 15 mM external K, the Na efflux was markedly stimulated; with 15 mM K the Na influx was 250 to 300 per cent greater than normal. On the other hand, Na influx was unchanged with 15 mM K. The stimulated Na efflux with the higher concentrations was not appreciably reduced when choline or Li was substituted for external Na, but was completely inhibited by 10-5 M strophanthidin. From these findings it is concluded that the active transport of Na is stimulated by the higher concentrations of K. It is postulated that this effect on the Na "pump" is produced as a result of the depolarization of the muscle membranes and is related to the increased metabolism and heat production found under conditions of high external K.

scholarly journals Effects of Sodium Azide on Sodium Fluxes in Frog Striated Muscle

1965 ◽  
Vol 48 (3) ◽  
pp. 515-525 ◽  
Author(s):  
Paul Horowicz ◽  
Carl J. Gerber
Keyword(s):  
Active Transport ◽  
Sodium Azide ◽  
Transmembrane Potential ◽  
Striated Muscle ◽  
Membrane Depolarization ◽  
The Other ◽  
Similar Increase ◽  
Other Hand ◽  
Na Efflux ◽  
Stimulation Of

Unidirectional Na fluxes from frog's striated muscle were measured in the presence of 0 to 5 mM sodium azide. With azide concentrations of 2 and 5 mM the Na efflux was markedly stimulated; the Na efflux with 5 mM azide was about 300 per cent greater than normal. A similar increase was present when all but the 5.0 mM sodium added with azide was replaced by choline. 10-5 M strophanthidin abolished the azide effect on Na24 efflux. Concentrations of azide of 1.0 mM or less had no effect on Na efflux. The Na influx, on the other hand, was only increased by 41 per cent in the presence of 5 mM NaN3. From these findings it is concluded that the active transport of Na is stimulated by the higher concentrations of azide. The hypothesis is advanced that the active transport of Na is controlled by the transmembrane potential and that the stimulation of Na efflux is produced as a consequence of the membrane depolarization caused by the azide.

scholarly journals The Transport of Salt and Water across Isolated Rat Ileum

1967 ◽  
Vol 50 (3) ◽  
pp. 695-727 ◽  
Author(s):  
T. W. Clarkson
Keyword(s):  
Active Transport ◽  
Transport Processes ◽  
Irreversible Processes ◽  
Pressure Gradients ◽  
Ion Flow ◽  
Chemical Gradients ◽  
In Series ◽  
Frictional Coefficients ◽  
The Relationship ◽  
Active Channel

The flows of sodium, potassium, and chloride under electrical and chemical gradients and of salt and water in the presence of osmotic pressure gradients are described by phenomenological equations based on the thermodynamics of irreversible processes. The aim was to give the simplest possible description, that is to postulate the least number of active transport processes and the least number of separate pathways across the intestine. On this basis, the results were consistent with the following picture of the intestine: Two channels exist across this tissue, one allowing only passive transport of ions and the other only active. In the passive channel, the predominant resistance to ion flow is friction with the water in the channel. The electroosmotic flow indicates that the passive channel is lined with negative fixed charged groups having a surface charge density of 3000 esu cm-2. The values of the ion-water frictional coefficients, and the relationship between ionic concentrations and flows indicate that the passive channel is extracellular. The active channel behaves as two membranes in series, the first membrane being semipermeable but allowing active transport of sodium, and the second membrane being similar to the passive channel. Friction with the ions in the second "membrane" is the predominant resistance to water flow.

scholarly journals The ionic basis of the hypo-osmotic depolarization in neurons from the opisthobranch mollusc Elysia chlorotica

1992 ◽  
Vol 163 (1) ◽  
pp. 169-186
Author(s):  
R. H. Quinn ◽  
S. K. Pierce
Keyword(s):  
Cell Volume ◽  
Time Course ◽  
The Other ◽  
Resting Potential ◽  
Ion Concentrations ◽  
Elysia Chlorotica ◽  
Apparent Relationship ◽  
Volume Recovery ◽  
Original Potential ◽  
Ionic Basis

The resting potential of identified cells (Parker cells) in the abdominal ganglion of Elysia chlorotica (Gould) depolarizes by about 30 mV in response to a 50% reduction in osmolality and returns to the original potential in 20 min. Cell volume recovery requires approximately 2 h. Thus, recovery of the resting potential is not dependent on recovery of cell volume. The hypo-osmotic depolarization persists following inhibition of the electrogenic Na+/K(+)-ATPase with ouabain, and the levels of extracellular K+ and Cl- have little effect on the magnitude of the depolarization, while decreasing extracellular Na+ concentration produces a depolarization of only 10 mV. This suggests that the hypo-osmotic depolarization in Parker cells results mostly from increased relative permeability to Na+. Following transfer from 920 to 460 mosmol kg-1, Na+, Cl- and proline betaine leave the cells while intracellular K+ is conserved. Loss of intracellular Na+ and conservation of intracellular K+ are dependent on active transport by the Na+/K(+)-ATPase. Na+ and proline betaine leave the cells with a time course that is much longer than that of the hypo-osmotic depolarization. Unlike the other solutes, most of the reduction in intracellular Cl- concentration occurs coincidentally with the hypo-osmotic depolarization. However, unlike the hypo-osmotic depolarization, bulk loss of Cl- does not require the reduction in osmolality, only the reduction in extracellular ion concentrations. There is no apparent relationship between membrane depolarization and the regulation of intracellular osmolytes in Elysia neurons following hypo-osmotic stress.

The effects of transecting the IXth and Xth cranial nerves on hydromineral balance in the eel Anguilla anguilla

1976 ◽  
Vol 64 (2) ◽  
pp. 461-475
Author(s):  
N. Mayer-Gostan ◽  
T. Hirano
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Cranial Nerves ◽  
Anguilla Anguilla ◽  
Vagus Nerves ◽  
Rapid Reduction ◽  
Ion Concentrations ◽  
Excess Loss ◽  
Na Efflux ◽  
Hydromineral Balance

The IXth and the Xth cranial nerves in Anguilla anguilla were transected, and the effects upon ion and water balance were studied in fresh water and sea water, and during transfer from fresh water and vice versa. In fresh water there is a slow demineralization due to an excess loss of Na and Cl ions. During freshwater to seawater transfer the eel survives only for 4–5 days. The fish do not drink and Na efflux does not increase enough to extrude excess ions. In sea water the glossopharyngeal and vagus nerves are necessary for the maintenance of the hydromineral balance. Denervation is followed by an increase in plasma ion concentrations. Na fluxes are not modified and increased water loss is not compensated by drinking. The rapid reduction of Na efflux during transfer from sea water to fresh water is not modified by denervation.

The Dogfish Neuromuscular Junction: Dual Innervation of Vertebrate Striated Muscle Fibres?

1972 ◽  
Vol 10 (3) ◽  
pp. 657-665
Author(s):  
Q. BONE
Keyword(s):  
Neuromuscular Junction ◽  
Nerve Terminal ◽  
Striated Muscle ◽  
Dense Core ◽  
The Other ◽  
Muscle Fibres ◽  
Nerve Terminals ◽  
Nerve Fibres ◽  
Different Types ◽  
Motor End Plate

In the myotomal muscles of the dogfish, Scyliorhinu canicula, there are 2 major types of fibre. The red fibres at the periphery of the myotome receive a distributed en grappe pattern of innervation. There are subjunctional folds at these endings, and the nerve terminals contain vesicles around 50 nm in diameter. In contrast to this, the white twitch fibres of the myotome are innervated focally, by 2 nerve fibres passing to the same motor end-plate. These 2 fibres contain vesicles of different types. One type of nerve terminal contains vesicles around 50 nm in diameter; these terminals resemble those upon the red fibres. The other contains vesicles up to 100 nm in diameter, frequently possessing a dense core. It is suggested that the white twitch fibres of dogfish are innervated by 2 separate axons, possibly containing different transmitter substances.

Effect of cellular determination on oncogenic transformation by chemicals and oncogenes

1988 ◽  
Vol 8 (10) ◽  
pp. 4322-4327
Author(s):  
M A Harrington ◽  
F Gonzales ◽  
P A Jones
Keyword(s):  
Striated Muscle ◽  
Myogenic Differentiation ◽  
Cell Types ◽  
Soft Agar ◽  
The Other ◽  
Ras Oncogene ◽  
Oncogenic Transformation ◽  
Ras Gene ◽  
Embryo Cells ◽  
End Stage

Three developmentally determined myogenic cell lines derived from C3H 10T1/2 C18 (10T1/2) mouse embryo cells treated with 5-azacytidine were compared with the parental 10T1/2 line for their susceptibility to oncogenic transformation by 3-methylcholanthrene or the activated human c-Ha-ras oncogene. Neither the 10T1/2 cells nor the myogenic derivatives grew in soft agar or formed tumors in nude mice. In contrast to 10T1/2 cells, the three myogenic derivatives were not susceptible to transformation by 3-methylcholanthrene, so that cellular determination altered the response of 10T1/2 cells to chemical carcinogen. On the other hand, all cell types were transformed to a tumorigenic phenotype following transfection with the activated c-Ha-ras gene. The transfected myogenic cells expressed both the c-Ha-ras gene and the muscle determination gene MyoD1. In contrast to other reports, the presence of as many as six copies of the c-Ha-ras gene per genome did not prevent the formation of striated muscle cells which expressed immunologically detectable muscle-specific myosin. The expression of the c-Ha-ras gene does not therefore necessarily preclude the expression of the determination gene for myogenesis or prevent end-stage myogenic differentiation.

Electric current generated by squid giant axon sodium pump: external K and internal ADP effects

1978 ◽  
Vol 235 (1) ◽  
pp. C63-C68 ◽  
Author(s):  
R. F. Abercrombie ◽  
P. de Weer
Keyword(s):  
Sodium Pump ◽  
Giant Axon ◽  
Pump Current ◽  
Membrane Resistance ◽  
Extracellular Potassium ◽  
Sodium Efflux ◽  
Steroid Sensitive ◽  
External Potassium ◽  
Loligo Pealei ◽  
External K

The operation of the sodium pump of giant axons of the squid, Loligo pealei, has been studied simultaneously in two independent ways: 1) by measuring sodium efflux with 22Na, and 2) by calculating the transmembrane current generated by the pump from measurements of membrane resistance and digitalis-sensitive membrane potential. In normal, untreated axons, the effect of increasing the external potassium concentration on both sodium efflux and pump current is similar, which suggests that Na:K pump stoichiometry remains relatively constant in the range of 0-20 mM external K. The data are compatible with a 3:2 Na:K ratio. In axons whose intracellular ADP level has been elevated by injection of L-arginine, a large, electrically silent, cardiotonic steroid-sensitive sodium efflux takes place in the absence of external potassium; this suggests that pump-mediated Na:Na exchange is 1:1 or electroneutral. Finally, elevation of external potassium levels causes the appearance, in high-ADP axons, of electrogenic pumping, with little effect on sodium efflux; hence, in contrast to what is seen in normal (low-ADP) axons, the charge translocated, per sodium ion extruded, increases sharply with increasing extracellular potassium levels.

scholarly journals Cellular and Animal Models of Striated Muscle Laminopathies

Cells ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 291 ◽  
Author(s):  
Hannah A. Nicolas ◽  
Marie-Andrée Akimenko ◽  
Frédérique Tesson
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscles ◽  
Molecular Mechanisms ◽  
Striated Muscle ◽  
Nuclear Lamina ◽  
The Other ◽  
Lamin A ◽  
Lmna Gene ◽  
Future Directions ◽  
Exon 10

The lamin A/C (LMNA) gene codes for nuclear intermediate filaments constitutive of the nuclear lamina. LMNA has 12 exons and alternative splicing of exon 10 results in two major isoforms—lamins A and C. Mutations found throughout the LMNA gene cause a group of diseases collectively known as laminopathies, of which the type, diversity, penetrance and severity of phenotypes can vary from one individual to the other, even between individuals carrying the same mutation. The majority of the laminopathies affect cardiac and/or skeletal muscles. The underlying molecular mechanisms contributing to such tissue-specific phenotypes caused by mutations in a ubiquitously expressed gene are not yet well elucidated. This review will explore the different phenotypes observed in established models of striated muscle laminopathies and their respective contributions to advancing our understanding of cardiac and skeletal muscle-related laminopathies. Potential future directions for developing effective treatments for patients with lamin A/C mutation-associated cardiac and/or skeletal muscle conditions will be discussed.

scholarly journals Relative Ion Permeabilities in the Crayfish Giant Axon Determined from Rapid External Ion Changes

1967 ◽  
Vol 50 (7) ◽  
pp. 1929-1953 ◽  
Author(s):  
Alfred Strickholm ◽  
B. Gunnar Wallin
Keyword(s):  
Membrane Potential ◽  
Potassium Level ◽  
Potassium Concentration ◽  
Giant Axon ◽  
Resting Potential ◽  
Resting Membrane Potential ◽  
Constant Field ◽  
Appreciable Effect ◽  
Ion Concentrations ◽  
External Potassium

The changes in membrane potential of isolated, single crayfish giant axons following rapid shifts in external ion concentrations have been studied. At normal resting potential the immediate change in membrane potential after a variation in external potassium concentration is quite marked compared to the effect of an equivalent chloride change. If the membrane is depolarized by a maintained potassium elevation, the immediate potential change due to a chloride variation becomes comparable to that of an equivalent potassium change. There is no appreciable effect on membrane potential when external sodium is varied, at normal or at a depolarized membrane potential. Starting from the constant field equation, expressions for the permeability ratios PCl/PK, PNa/PK, and for intracellular potassium and chloride concentrations are derived. At normal resting membrane potential, PCl/PK is 0.13 but at a membrane potential of -53 mv (external potassium level increased about five times) it is 0.85. The intracellular concentrations of potassium and chloride are estimated to be 233 and 34 mM, respectively, and it is pointed out that this is not compatible with ions distributed in a Nernst equilibrium across the membrane. It is also stressed that the information given by a plot of membrane potential vs. the logarithm of external potassium concentrations is very limited and rests upon several important assumptions.

Effects of dinitrophenol on active-transport processes and cell membranes in the Malpighian tubule of Formica

1994 ◽  
Vol 428 (2) ◽  
pp. 150-156 ◽  
Author(s):  
S. Dijkstra ◽  
E. Lohrmann ◽  
E. Van Kerkhove ◽  
P. Steels ◽  
R. Greger
Keyword(s):  
Active Transport ◽  
Cell Membranes ◽  
Malpighian Tubule ◽  
Transport Processes
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