The stoicheiometry of sodium ion movement from frog muscle

Harris, Emma

doi:10.1113/jphysiol.1967.sp008370

Cited by 12 publications

(2 citation statements)

References 8 publications

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“…Thus Baker (1965) calculated that for the Na pump in crab axons the ATP:Na ratio was close to 1: 3, and Baker & Shaw (1965) concluded that this ratio probably also applied to squid giant axons. For frog muscle, Dydynska & Harris (1966) and Harris (1967) showed that the ATP:Na ratio was also close to 1: 3. Since this ratio is the same as in red blood cells, it seems reasonable to suggest that the Na: K ratio is also the same, and that the ratio for the Na pump in snail neurones might well be 3Na: 2K.…”

Section: Discussionmentioning

confidence: 91%

Membrane current and intracellular sodium changes in a snail neurone during extrusion of injected sodium

Thomas¹

1969

The Journal of Physiology

249

141

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1. Sodium was injected into an identified snail neurone by passing current between two intracellular micro‐electrodes, the membrane potential being recorded with a third micro‐electrode. 2. The injection of about 25 p‐equiv Na, but not the injection of similar quantities of K or Li, caused a hyperpolarization of up to 20 mV. This response to Na injection was blocked by application of ouabain or removal of external K, indicating that it was due to the stimulation of an electrogenic pump. 3. To measure the current produced by the sodium pump the output of a feed‐back amplifier was fed into the cell via a fourth intracellular micro‐electrode so as to keep the average membrane potential constant. The pump current, measured in this way, rose at a constant rate during, and declined exponentially after, an injection of Na, the decline having an average time constant of 4·4 min. The total charge transferred by the pump was between a third and a quarter of the charge passed to inject sodium. 4. An intracellular Na‐sensitive glass micro‐electrode was used to follow changes in the concentration of intracellular Na ions. The results showed that both the pump current and the rate of Na extrusion were proportional to the concentration of intracellular Na ions above the normal level. 5. It was concluded that about two thirds of the Na extruded was coupled to the active transport of other ions, probably to the uptake of K, the uncoupled third producing the electrogenic effect.

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Section: Discussionmentioning

confidence: 91%

Membrane current and intracellular sodium changes in a snail neurone during extrusion of injected sodium

Thomas¹

1969

The Journal of Physiology

249

141

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“…If J, in Table III decreases exponentially with the time constant r = 30 min, its average value during the first hour in recovery solution is 57% of its initial value, or between 10 and 16 pmoles/cm2 per sec. Under similar conditions, but with dinitrofluorobenzene in the solution (which inhibits ATP synthesis) muscle ATP is hydrolyzed at a rate of 7.7-18.6 mM/kg per hr (Dydynska and Harris, 1966;Harris, 1967). For r = 40 u and for fiber water = 650 cm2/kg wet weight, J, = 6-12 pmoles ATP/cm2 per sec over 1 hr and is within the range given in Table III.…”

Section: Discussionmentioning

confidence: 56%

The Sodium-Potassium Exchange Pump

Rapoport¹

1971

Biophysical Journal

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A model for the Na-K exchange pump was applied to data on Na(+)-loaded frog sartorius muscle, and was used to relate the rate of adenosine triphosphate (ATP) hydrolysis to the electrical properties of the cell membrane. Membrane hyperpolarization was considered to arise from an electrical current which was produced by the hydrolysis reaction coupled to ion movements, and which flowed across the membrane. The reaction rate, as calculated from hyperpolarization, agreed with direct measurements of ATP hydrolysis and with the rate estimated from Na(+) tracer efflux studies. Although Na(+) is actively extruded, the model showed that K(+) is inwardly transported if the potassium permeability of the membrane is less than about 6.6 x 10(-6) cm/sec, as is suggested by resistance data. Calculations indicated that the reaction conductance L(rr) was relatively constant when compared with the reaction rate and reaction free energy for large changes in internal and external ionic concentrations. Its value agreed with the value obtained from the dependence of Na(+) tracer efflux on external K(+). A set of experiments was suggested which would provide a more complete interpretation of the data.

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Energetics of Muscle Contraction

Kushmerick

1983

Comprehensive Physiology

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The sections in this article are: Historical Perspectives Nature of the Muscle Machine Chemical Discoveries Energetics as an Analytical Tool Direct Measurements of Chemical Change Summary Chemical Reactions and Metabolic Principles Adenosine Triphosphatases Creatine Phosphokinase Adenylate Kinase Adenylate Deaminase and the Purine Nucleotide Cycle Glycogenolysis and Glycolysis Oxidative Metabolism Basic Energetic Model Thermodynamics Energy Balance Myothermic Method Biochemical Method Results of Energy Balance Experiments Energy Balance Studies in Rana temporaria Energy Balance Studies in Rana pipiens Amphibian Muscles Mammalian Muscles Energetics of Muscles that Shorten or are Stretched New Directions Phosphorus Nuclear Magnetic Resonance Spectroscopy Use of Single Fibers

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The stoicheiometry of sodium ion movement from frog muscle

Cited by 12 publications

References 8 publications

Membrane current and intracellular sodium changes in a snail neurone during extrusion of injected sodium

Membrane current and intracellular sodium changes in a snail neurone during extrusion of injected sodium

The Sodium-Potassium Exchange Pump

Energetics of Muscle Contraction

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