An analysis of the end‐plate potential recorded with an intra‐cellular electrode

Fatt, P.; Katz, Bernard

doi:10.1113/jphysiol.1951.sp004675

Cited by 1,339 publications

(768 citation statements)

References 11 publications

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“…Evoked EPPs and miniature end-plate potentials (MEPPs) were recorded in the conventional way (Fatt and Katz, 1951), with intracellular electrodes filled with KCl (3 M) and 10 -20 M⍀ resistance, inserted in the motor end plate. The reference electrode was an Ag-AgCl pellet.…”

Section: Electrophysiology Recordingsmentioning

confidence: 99%

Neuromuscular transmission modulation by adenosine upon aging

Pousinha

Correia

Sebastião

et al. 2012

Neurobiology of Aging

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In infant rats adenosine A 2A receptor-mediated modulation of neuromuscular transmission predominates over A 1 receptor-mediated neuromodulation. We investigated whether aging affects this A 2A /A 1 receptor balance. Evoked (EPPs) and miniature end plate potentials (MEPPs) were recorded from single fibers of (weeks-old) infant (3-4), young adult (12-16), older (36 -38), and aged (80 -90) male rat-diaphragm. The non A 1 /A 2A selective agonist, 2-chloroadenosine (CADO; 30 nM) and the adenosine kinase inhibitor, iodotubericidin (ITU; 10 M) increased mean amplitude and quantal content of EPPs in infant, young adult, and older adult rats, but not in aged rats. The facilitatory effects were prevented by the A 2A receptor antagonist, ZM241385 (50 nM) and mimicked by the A 2A receptor agonist, CGS21680 (10 nM). The A 1 receptor agonist, 6-cyclopentyladenosine (CPA; 100 nM), decreased EPPs amplitude in all age groups. It is concluded that aging differently influences adenosine A 1 receptor and A 2A receptor-mediated presynaptic modulation of neuromuscular transmission, so that the facilitatory influence decreases upon aging, whereas the inhibitory influence remains unchanged in aged animals. The reduction of adenosine A 2A receptors upon aging may contribute to the age-related changes in neuromuscular function.

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Section: Electrophysiology Recordingsmentioning

confidence: 99%

Neuromuscular transmission modulation by adenosine upon aging

Pousinha

Correia

Sebastião

et al. 2012

Neurobiology of Aging

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“…Optimal muscle length (L o ) and supramaximal stimulation voltage (~80 V) were determined from micromanipulations of muscle length and a series of twitch contractions (1 Hz squarewave pulse, 1.0 ms duration) until twitch tension was maximal = maximum isometric twitch force (P t ). Although a 2.0 ms pulse duration approximates the normal excitation duration when occurring through neuromuscular transmission (Fatt and Katz, 1951), we used a 1.0 msec pulse duration to eliminate the chance of multiple twitches (Chervu et al, 1989).…”

Section: Direct Muscle Stimulation-mentioning

confidence: 99%

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

Croes

Bartheld

2007

Journal of Neuroscience Methods

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Contractile forces can be measured in situ and in vitro. To maintain metabolic viability with sufficient diffusion of oxygen, established guidelines for in vitro skeletal muscle preparations recommend use of relatively thin muscles (≤1.25 mm thick). Nevertheless, forces of thin extraocular muscles vary substantially between studies. Here, we examined parameters that affect force measurements of in situ and in vitro preparations, including blood supply, nerve stimulation, direct muscle stimulation, muscle size, oxygenated or non-oxygenated buffer solutions, and the time after interruption of vascular circulation. We found that the absolute forces of extraocular muscle are substantially lower when examined in vitro. In vitro preparation of 0.58 mm thick extraocular muscle from 3-week old birds underestimated contractile function, but not of thinner (0.33 mm) muscle from 2-day old birds. Our study shows that the effective criteria for functional viability, tested in vitro, differ between extraocular and other skeletal muscle. We conclude that contractile force of extraocular muscles will be underestimated by between 10 and 80%, when measurements are made after cessation of blood supply (at 5 -40 min). The mechanisms responsible for the declining values for force measurements are discussed, and we make specific recommendations for obtaining valid measurements of contractile force.

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“…The micropipettes were placed 50-200 ,um apart. Rectangular pulses of current with a duration of 30-125 msec were used to stimulate directly the fibres and to measure the effective resistance between the inside and the outside of the cells (Fatt & Katz, 1951). In most fibres direct current was also applied to polarize the fibres to membrane potentials of -70 to -80 mV.…”

Section: Methodsmentioning

confidence: 99%

“…End-plate potentials (e.p.p.s) (Fatt & Katz, 1951) were evoked by nerve stimulation in nerve-muscle preparations in which synaptic transmission was partially blocked with 1 0 to 2 0 x 10-6 M D-tubocurarine to prevent the firing of action potentials by the fibres. E.p.p.s were recorded in the innervation zone.…”

Section: Focally Innervated Fibresmentioning

confidence: 99%

Electrophysiological identification of two types of fibres in rat extraocular muscles.

Chiarandini¹,

Stefani²

1979

The Journal of Physiology

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SUMMARY1. The synaptic potentials and electrical properties of rat inferior rectus muscles were examined in vitro.2. In most fibres the spontaneous synaptic activity consisted of typical miniature end-plate potentials which had a normal distribution of amplitudes and rather uniform time courses. Suprathreshold and maximal nerve stimulation evoked unitary end-plate potentials (e.p.p.s). The synaptic activity of these fibres could be recorded only in the innervation zone of the muscle. These fibres were identified as being focally innervated.3. Focally innervated fibres gave action potentials upon direct and indirect stimulation. They had an effective resistance (Reff) of 1'62 + 022 MQ (mean + S.E., twenty-two fibres) and a time constant (Tm) of 3-8 + 04 msec (twenty-one fibres).Voltage-current curves in control saline were linear between membrane potentials of -50 to -140mV. 4. In a small number of fibres the spontaneous synaptic activity consisted of miniature small-nerve junction potentials which had a skewed distribution of amplitudes with predominance of smaller voltages and time courses with a wide range of variation. Nerve stimulation evoked composite small-nerve junction potentials (s.j.p.s) which could be resolved into unitary components by varying the strength of stimulation. S.j.p.s had a higher threshold than e.p.p.s. Synaptic potentials could be recorded outside the innervation zone, at various sites along the muscle length. These fibres were recognized as being multiply innervated with polyneuronal innervation.5. Multiply innervated fibres lacked action potentials, had a large Reff of 6-0 + 1-1 MD (six fibres) and a prolonged Tm of 29-8 + 4*8 msec. Reff show a moderate decrease to hyperpolarization and a rather large decrease to depolarization which denote, respectively, the presence of anomalous and delayed rectification.6. It is concluded that rat extraocular muscles contain at least two populations of muscle fibres that in terms of synaptic activity and electrical properties are comparable to twitch fibres of other mammalian muscles and to slow or tonic fibres of amphibians.

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An analysis of the end‐plate potential recorded with an intra‐cellular electrode

Cited by 1,339 publications

References 11 publications

Neuromuscular transmission modulation by adenosine upon aging

Neuromuscular transmission modulation by adenosine upon aging

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

Electrophysiological identification of two types of fibres in rat extraocular muscles.

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