The effects of hypoxia on neuromuscular transmission in a mammalian preparation

Hubbard, J. I.; Løyning, Y

doi:10.1113/jphysiol.1966.sp007982

Cited by 52 publications

(17 citation statements)

References 29 publications

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“…The m.e.p.p. frequency was determined either by counting photographed oscilloscope traces or by using a counting system similar to that described by Andersen & Curtis (1964), with the precautions described by Hubbard & Loyning (1966). After suitable amplification and discrimination m.e.p.p.s triggered a pulse generator and were counted over periods of 10-30 sec (Hewlett Packard Counter Type 52332 with Digital Output Type 562A).…”

Section: Methodsmentioning

confidence: 99%

“…The diaphragms and attached nerve were mounted in a divided recording bath and bathed by a continuously flowing solution kept at 32.9-34.5°C in all experiments except in some of those involving change-over of bathing solutions. The range was then 30-531-5' C. The heating and temperature monitoring system have been previously described (Hubbard & Loyning, 1966).…”

Section: Methodsmentioning

confidence: 99%

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On the mechanism by which calcium and magnesium affect the spontaneous release of transmitter from mammalian motor nerve terminals

Hubbard¹,

Jones²,

Landau³

1968

The Journal of Physiology

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210

114

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SUMMARY1. The frequency of miniature end-plate potentials (m.e.p.p.s) was recorded from neuromuscular junctions in rat diaphragm phrenic nerve preparations in vitro after preparations had soaked in solutions containing Ca in concentrations between 10-10 and 10-2 M and a similar range of [Mg].2. Ethylenediamine tetra-acetate (EDTA) and ethyleneglycol bis (/3-aminoethyl ether) tetra-acetate (EGTA) buffers were added to prepare solutions with [Ca]

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

On the mechanism by which calcium and magnesium affect the spontaneous release of transmitter from mammalian motor nerve terminals

Hubbard¹,

Jones²,

Landau³

1968

The Journal of Physiology

Self Cite

210

114

View full text Add to dashboard Cite

show abstract

“…Since the mammalian neuromuscular junction is sensitive to hypoxia (Hubbard & L0yning, 1966), the dissection was done in two stages: both the soleus and the gastrocnemius muscle were dissected rapidly from an anaesthetized rat (ether) and transferred to a dish containing oxygenated mammalian Ringer-Locke solution, where the soleus nerve-muscle preparation was isolated. The preparation was perfused throughout the experiment with oxygenated solution constantly bubbled with 95 % oxygen and 5% carbon dioxide.…”

Section: Preparationmentioning

confidence: 99%

Ionic basis of tetanic and post‐tetanic potentiation at a mammalian neuromuscular junction.

Nussinovitch¹,

Rahamimoff²

1988

The Journal of Physiology

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SUMMARY1. The ionic basis of tetanic and post-tetanic potentiation (TP and PTP) was studied at the rat soleus neuromuscular junction (NMJ), using the miniature endplate potential (MEPP) frequency as an index for transmitter release. Conventional intracellular recording and computer-assisted data analysis were employed.2. The experimental results in this study indicate that contrary to previous suggestions, there is a substantial similarity in the ionic basis of TP and PTP at the mammalian and amphibian motor nerve terminals which can be subdivided into [Ca2+]0-dependent and [Ca2+]0-independent parts.3. Tetanic and post-tetanic increase in MEPP frequency at the rat soleus NMJ is similar to that at the frog NMJ in the following aspects: (i) Tetanic potentiation is substantially larger in calcium-containing solutions than in calcium-deficient solutions. About 90 % of tetanic potentiation is contributed by extracellular calcium. 6. Tetanic potentiation is manifested earlier in calcium-containing media than in calcium-deficient media. This difference may indicate that sodium entry into the terminal during tetanic stimulation is at locations remote from the releasing sites. Alternatively, this time difference may be due to the delay between intracellular sodium accumulation and the increase in transmitter release.

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“…When one uses the standard oxygenation technique, Krebs solution simply cannot meet such a high demand for oxygen. (Creese, 1954;Creese et al, 1958;Calkins et al, 1954;Hubbard andLoyning, 1956, Paul, 1961). With the use of fluorocarbon emulsion it should be possible further to clarify the actual events which occur at the synapse.…”

Section: Discussionmentioning

confidence: 99%

“…Numerous studies (Creese et al, 1958;Paul, 1961;Hubbard and Loyning, 1966) have shown that electrophysiological events at the neuromuscular]unction are easily altered by slight differences in the degree of oxygenation. In vitro preparations are bathed in a physiological salt solution and bubbled with oxygen.…”

Section: Introductionmentioning

confidence: 99%

Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro.

Wong¹,

DiMicco²,

Standaert³

et al. 1977

The Journal of General Physiology

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A B s T R A c T The effects of liquid fluorocarbons as bathing media were determined by use of in vitro neuromuscular preparations. Rat hemidiaphragms were bathed in either oxygenated fluorocarbon (FC) emulsion or standard oxygenated Krebs solution. Contractile force in response to simple supramaximal nerve stimuli as well as to high frequency stimulation was greater, while twitch:tetanus ratio was smaller in FC emulsion. With such medium, post-tetanic potentiation of contraction was also more consistently observed. Indirectly stimulated diaphragms survived longer in FC emulsion. After cessation of oxygenation, oxygen tension (pO2) of the medium declined more rapidly with Krebs than with FC emulsion; pO2 directly correlated with force of contraction. Similarly, in the chick biventer cervicis preparation, FC emulsion enhanced nerve-stimulated force of contraction; returning the preparation to standard Krebs solution reversed this phenomenon. Dose-response curves of muscle contraction in response to acetylcholine and KC1 administration were shifted upward during FC emulsion superfusion. Frequency of miniature endplate potentials was lower in FC emulsion than that observed in Krebs solution, measured from the same cell of the rat diaphragm. Resting membrane potentials were also greater in muscle cells sampled from FC emulsion-bathed preparations. These data suggest that FC emulsion is superior to standard Krebs solution as a bathing medium for in vitro neuromuscular preparations by virtue of the high solubility of oxygen in it.

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The effects of hypoxia on neuromuscular transmission in a mammalian preparation

Cited by 52 publications

References 29 publications

On the mechanism by which calcium and magnesium affect the spontaneous release of transmitter from mammalian motor nerve terminals

On the mechanism by which calcium and magnesium affect the spontaneous release of transmitter from mammalian motor nerve terminals

Ionic basis of tetanic and post‐tetanic potentiation at a mammalian neuromuscular junction.

Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro.

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