The free amino-acids of invertebrate nerve

Lewis, P. R.

doi:10.1042/bj0520330

Cited by 133 publications

(30 citation statements)

References 16 publications

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“…This observation probably indicates that some substance is released into the junctional region by local damage. Since crab nerve is known to contain high concentrations of free glutamate (Lewis, 1952;Baker & Potashner, 1971) it seems reasonable that the signal may arise from a continuous release of this substance when the nerve terminals are damaged by the focal electrode. In these experiments recording was terminated if a spot developed this noise signal.…”

Section: L-glutamate Voltage Noisementioning

confidence: 99%

On the elementary conductance event produced by L‐glutamate and quanta of the natural transmitter at the neuromuscular junctions of Maia squinado.

Crawford¹,

McBurney²

1976

The Journal of Physiology

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1. The membrane potential of giant muscle fibres of Maia squinado was measured with an intracellular wire electrode. On applying L‐glutamate to the fibre the cell deplorized and fluctuations of the membrane potential around its mean level‐‐glutamate noise‐‐were seen. 2. The variance of the glutamate voltage noise is proportional to the mean level of depolarization. The noise can be regarded as being caused by numerous exponentially decaying elementary voltage events about 5 X 10(‐10) V in amplitude. The miniature excitatory junctional potential (min.e.j.p.) is approximately 6000 times the amplitude of the elementary voltage event produced by L‐glutamate. 3. The power spectrum of glutamate voltage noise is a Lorentzian with a half‐power frequency of approximately 20 Hz. 4. Min. e.j.p.s. decay exponentially with a time constant that coincides with the average lifetime of the elementary glutamate voltage event. 5. When glutamate is applied locally to a spot where extracellular min. e.j.p.s. can be recorded with a focal glass pipette, extracellular glutamate noise is seen. Glutamate noise could not be detected from elsewhere on the fibre. 6. The variance of the extracellular noise is proportional to the mean extracellular potential, and its power spectrum is a Lorentzian with a half‐power frequency of about 110 Hz. 7. The extracellular min. e.j.p.s decay exponentially with a time constant that coincides with average lifetime of the elementary glutamate current event. 8. It is suggested that the decay of the quantal currents flowing at the excitatory junction is limited by the closure of the conductance channels in the post‐synaptic membrane and not by the relaxation of the transmitter concentration in the synaptic cleft.

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Section: L-glutamate Voltage Noisementioning

confidence: 99%

On the elementary conductance event produced by L‐glutamate and quanta of the natural transmitter at the neuromuscular junctions of Maia squinado.

Crawford¹,

McBurney²

1976

The Journal of Physiology

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“…1% purified Fructosan (Palmer, 1951) was added to the Ringer in some experiments. The polysaccharide was estimated after 4-6 hr in muscle and solution, and the volume of extracellular water into which diffusion had taken place was computed as described by Lewis (1952). Control readings were given by muscles soaked under similar conditions but without polysaccharide.…”

mentioning

confidence: 99%

Electrical activity and intracellular sodium concentration in frog muscle

Desmedt¹

1953

The Journal of Physiology

162

103

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“…We now know much about the composition of the intracellular fluid of invertebrate nerves (e.g. Lewis, 1952) and one analysis has been made of the electrolyte distribution in frog nerves (Fenn, Cobb, Hegnauer & Marsh, 1934). No study of the distribution of electrolytes in mammalian nerves, however, is apparently available.…”

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confidence: 99%

The distribution of Na and K in cat nerves

Krnjević¹

1955

The Journal of Physiology

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Ever since the first full statement of the membrane theory (Bernstein, 1912) it has been widely believed that the mechanism of nervous conduction depends upon certain important differences between the concentrations of electrolytes inside and outside the nerve fibre. Bernstein had no evidence on this point and he relied for his argument on what evidence was available from analyses of muscle. We now know much about the composition of the intracellular fluid of invertebrate nerves (e.g. Lewis, 1952) and one analysis has been made of the electrolyte distribution in frog nerves (Fenn, Cobb, Hegnauer & Marsh, 1934). No study of the distribution of electrolytes in mammalian nerves, however, is apparently available.Estimations of the total content of Na, K and Cl in various mammalian (1954): Na and K. The information to be derived from these values is unfortunately greatly limited by complete uncertainty about the relative proportions of intra-and extracellular fluid and the relative proportions of total intra-and extracellular Na, K, or Cl. The present paper is an analysis of the distribution of Na, K and Cl in cat nerves, based upon: (a) a comparison of the total Na, K and Cl contents of intact nerve trunks and desheathed nerve bundles; (b) studies of the diffusion of Na from desheathed nerve bundles; (c) a direct estimate of the intracellular space obtained from photomicrographs. METHODSAnimals. Most of the nerves analysed were from cats. A small number of nerves from rabbits, dogs and monkeys were also studied for comparison; the only estimations made, however, were of the total Na and K.The majority of the nerves were removed from cats which were in good condition, with their circulation intact, in the course of experiments under general anaesthesia, or in some cases, after * Beit Memorial Research Fellow.

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The free amino-acids of invertebrate nerve

Cited by 133 publications

References 16 publications

On the elementary conductance event produced by L‐glutamate and quanta of the natural transmitter at the neuromuscular junctions of Maia squinado.

On the elementary conductance event produced by L‐glutamate and quanta of the natural transmitter at the neuromuscular junctions of Maia squinado.

Electrical activity and intracellular sodium concentration in frog muscle

The distribution of Na and K in cat nerves

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