Pre- and post-junctional effects of 1-fluoro-2,4-dinitrobenzene at the frog neuromuscular junction

The Journal of Physiology
A M Edelson, W L Nastuk

Abstract

1. FDNB increased by 60-90% the depolarization of the end-plate produced by applied carbachol in frog sciatic nerve-sartorius muscle preparations.2. In partially curarized preparations, FDNB (0.4 mM) increased the amplitude of the end-plate potential by a factor of 1.8.3. The quantal content of end-plate potentials was increased by FDNB (2 mM) as determined by the method of failures.4. After approximately 25-35 min, neuromuscular transmission was blocked by 0.4 mM-FDNB, as evidenced by abolition of neurally elicited end-plate potentials. At this stage miniature end-plate potentials could still be recorded, which indicates that the neuromuscular block was presynaptic.5. FDNB (0.4 mM) increased miniature end-plate potential frequency several hundred-fold when the Ringer solution contained normal calcium concentration (1.8 mM) or 0.45 mM calcium and 5.4 mM magnesium.6. During the first 60 min of exposure to 0.4 mM-FDNB there was a slight drop (4-6 mV) in resting potentials of muscle fibres. During this period directly initiated action potentials showed a marked decrease in the rate of repolarization and a small decrease in the amplitude and rate of rise.7. Using the technique of point voltage clamping in tetrodotoxin-treated muscl...Continue Reading

Citations

Jun 1, 1978·Neuropharmacology·K KaibaraA G Karczmar
Sep 1, 1974·Neuropharmacology·E K SilbergeldA M Goldberg
Jan 1, 1978·Progress in Neurobiology·E M Landau
Jul 1, 1975·British Journal of Pharmacology·I G Marshall, R L Parsons
Jul 1, 1975·British Journal of Pharmacology·I G Marshall, R L Parsons
Nov 1, 1987·British Journal of Pharmacology·T Hattori, H Maehashi

Related Concepts

Nerve Impulses
Metazoa
Salientia
Calcium
Carboptic
Electric Stimulation Technique
Electrophysiology (Science)
Fluorides
Iontophoresis
Magnesium

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