The effects of protoveratrine and germines on the release of acetylcholine from the auerbach plexus of the guinea-pig ileum

Vízi, E. S.; Foldes, Francis F.; Theunissen, J.

doi:10.1007/bf01249765

Cited by 7 publications

(2 citation statements)

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“…When trains of 30 stimuli .were applied with varying train intervals, the corrected ACh output per train was independent from the train interval. This is in contrast to the effects of protoveratrine and germines on this preparation, which do not increase volley output of ACh, but significantly increase ACh release during train intervals (Vizi et al, 1975). These effects of protoveratrine and germines caused by increased propagated activity have been attributed to enhanced sodium influx into the nerve fiber (Ulbricht, 1969";Varga et al, 1972).…”

Section: Discussionmentioning

confidence: 92%

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The effect of 4-aminopyridine on acetylcholine release

Vizi

Dijk

Foldes

1977

J. Neural Transmission

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The effect of 2-, and 4-aminopyridine (4-APYR) on the release mechanism of acetylcholine (ACh) from the nerve terminals of the Auerbach plexus-longitudinal muscle preparation of the guinea-pig ileum, suspended in eserinized Krebs' solution, was investigated. 2- and 4-APYR increased the release of ACh from the nerve terminals at rest and at both low and high frequency stimulation. The enhanced ACh release was found to be due to increased volley output. At lower frequency of stimulation, potentiation of ACh release was much higher than at higher rate of stimulation. 4-APYR was able to increase ACh release in the absence of [Ca2+]o. However, when a Ca-chelating agent, EDTA, was also added to the Ca-free Krebs' solution, 4-APYR was entirely ineffective. The depression of ACh release induced by Mg-excess was completely antagonized by 4-APYR. Tetrodotoxin (TTX) prevented augmentation of ACh release by 4-APYR. It is suggested that 4-APYR lowers the demand of nerve terminals for [Ca2+]o required for the excitation-secretion coupling process. The presence of a low concentration [Ca2+]o, however, is essential for the action of 4-APYR.

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Section: Discussionmentioning

confidence: 92%

“…Before the collection of the first sample, for assay, the strips were allowed to equilibrate for 60 min in the eserinized solution. The released ACh was bio-assayed on the isolated guinea-pig ileum at 33 ~ as described by Vizi, Foldes and Theunissen (1975).…”

Section: Measurement Of Ach Outputmentioning

confidence: 99%

The effect of 4-aminopyridine on acetylcholine release

Vizi

Dijk

Foldes

1977

J. Neural Transmission

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The influence of stimulation parameters on the potency and reversibility of neuromuscular blocking agents

Foldes

Chaudhry

Ohta

et al. 1981

J. Neural Transmission

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Voluntary muscle movements in mammalian muscles are initiated by short trains of 16 to 60 Hz impulses (Zierler, 1974). Despite this in most neurophysiological and neuropharmacological studies either single stimuli of 0.1 to 2 Hz or 5 to 10 sec 50 to 500 Hz tetani have been employed. Neither of these two types of stimuli are ideal for the testing of the functional integrity of the motor unit. Stimulation with single impulses, at slow rates, does not reveal incipient pathological or drug induced defects. Recovery of neuromuscular (NM) activity after 5 to 10 sec tetanic stimulation is prolonged and after repeated stimulation of this type the preparations decay rapidly. Stimulation of 0.1 sec trains of 50 Hz impulses applied every 10 to 20 sec eliminate the above disadvantages. This type of stimulation represents adequate challenge for revealing more moderate degrees of functional defects of the myoneural apparatus without causing rapid decay of the in vitro or in vivo preparations. In agreement with this the ED50 of NM blocking agents were found to be significantly lower in both the in vitro phrenic nerve-hemidiaphragm preparation and the in vivo sciatic nervetibialis anterior muscle preparation of rats during stimulation with 0.1 sec trains of 50 Hz impulses, than when single stimuli of 0.1 Hz were used. Recovery of the in vitro preparations after washout or in vivo after discontinuation of the infusion was also slower during stimulation with short trains of tetani. The antagonist potency of anticholinesterases or 4-aminopyridine and maximal recovery after the use of the optimal concentrations of these antagonists was less in the preparations stimulated with short trains of tetani than in those stimulated with single impulses.

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