scholarly journals Slow changes in currents through sodium channels in frog muscle membrane.

1983 ◽  
Vol 339 (1) ◽  
pp. 253-271 ◽  
Author(s):  
W Almers ◽  
P R Stanfield ◽  
W Stühmer
Keyword(s):  
Sodium Channels ◽  
Frog Muscle ◽  
Muscle Membrane

scholarly journals The Suppression of the Late After-Potential in Rubidium-Containing Frog Muscle Fibers

1965 ◽  
Vol 48 (6) ◽  
pp. 1003-1010 ◽  
Author(s):  
D. C. Hellam ◽  
D. A. Goldstein ◽  
L. D. Peachey ◽  
W. H. Freygang
Keyword(s):  
Membrane Potential ◽  
Potassium Concentration ◽  
Muscle Fibers ◽  
Frog Muscle ◽  
Muscle Membrane ◽  
Potassium Permeability ◽  
Intracellular Potassium ◽  
Intracellular Potassium Concentration

The late after-potential that follows trains of impulses in frog muscle fibers is virtually absent when most of the intracellular potassium is replaced by rubidium and the muscle is immersed in rubidium-containing Ringer's fluid. Its amplitude is also reduced in freshly dissected, potassium-containing muscle fibers that are immersed directly in Rb-Ringer's fluid. These findings are discussed in terms of the model for muscle membrane of Adrian and Freygang (1962 a, b) and in relation to the report of Adrian (1964) that Rb-containing muscle fibers do not exhibit the variations in potassium permeability as a function of membrane potential that are found in fibers with normal intracellular potassium concentration immersed in Ringer's fluid.

scholarly journals Binding of scorpion toxin to receptor sites associated with sodium channels in frog muscle. Correlation of voltage-dependent binding with activation.

1979 ◽  
Vol 74 (3) ◽  
pp. 375-391 ◽  
Author(s):  
W A Catterall
Keyword(s):  
Sodium Channels ◽  
Voltage Dependence ◽  
Binding Capacity ◽  
Specific Binding ◽  
Frog Muscle ◽  
Scorpion Toxin ◽  
Sartorius Muscle ◽  
Single Class ◽  
Bathing Medium ◽  
Toxin Binding

Purified scorpion toxin (Leiurus quinquestriatus) slows inactivation of sodium channels in frog muscle at concentrations in the range of 17-170 nM. Mono[125I]iodo scorpion toxin binds to a single class of sites in frog sartorius muscle with a dissociation constant of 14 nM and a binding capacity of 13 fmol/mg wet weight. Specific binding is inhibited more than 90% by 3 microM sea anemone toxin II and by depolarization with 165 mM K+. Half-maximal inhibition of binding is observed on depolarization to -41 mV. The voltage dependence of scorpion toxin binding is correlated with the voltage dependence of activation of sodium channels. Removal of calcium from the bathing medium shifts both activation and inhibition of scorpion toxin binding to more negative membrane potentials. The results are considered in terms of the hypothesis that activation of sodium channels causes a conformational change in the scorpion toxin receptor site resulting in reduced affinity for scorpion toxin.

Influence of Ethacrynic Acid on Muscle Surface Enzymes and of Ethacrynic Acid and Ouabain on Na, K, and H2O in Frog Muscle

1972 ◽  
Vol 50 (5) ◽  
pp. 432-444 ◽  
Author(s):  
J. R. Riordan ◽  
J. F. Manery ◽  
E. E. Dryden ◽  
T. S. Still
Keyword(s):  
Adenylate Kinase ◽  
Ethacrynic Acid ◽  
Narrow Range ◽  
Total Concentration ◽  
Frog Muscle ◽  
Muscle Membrane ◽  
Amp Deaminase ◽  
Passive Permeability ◽  
Minimum Concentration ◽  
Presence And Absence

Isolated frog muscles were exposed to concentrations of ethacrynic acid (2,3-dichloro-4-(2-methylene-butyryl)phenoxyaceticacid)ranging from 10−8 to 10−2 M. The diuretic (EA) at a concentration (10−3 M) which is sufficient to markedly inhibit net Na and K movements had no effect on three muscle surface enzymes (ATPase, adenylate kinase, 5′-AMP deaminase). The minimum concentration of EA required for inhibition of Na and K movement lies within the narrow range of 0.2 × 10−3 M to 10−3 M. The degree of inhibition increased with EA concentration up to 10−2 M. Concentrations of 0.2 × 10−3 M caused some contracture of the muscles as well. EA causes an increased K loss over that caused by ouabain alone both in the presence and absence of external Na. Na concentrations are not affected. Ouabain causes increased K loss over that caused by EA alone both in the presence and absence of external Na. Frog muscle has a component of K movement (about 35% of the total concentration) dependent upon external Na. This component is distinct from the ouabain-inhibited component and equal to the EA-inhibited component. The results are consistent with inhibition of the active transport of Na and K by EA as well as by ouabain and suggest that in the presence of Ca, EA also increases the passive permeability of the muscle membrane to K.

scholarly journals The potassium and chloride conductance of frog muscle membrane

1962 ◽  
Vol 163 (1) ◽  
pp. 61-103 ◽  
Author(s):  
R. H. Adrian ◽  
W. H. Freygang
Keyword(s):  
Frog Muscle ◽  
Chloride Conductance ◽  
Muscle Membrane
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