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Whole-cell voltage clamp and single-channel recordings were performed on cultured trigeminal ganglion neurons from quail embryos in order to study a sodium-activated potassium current (KNa). When KNa was activated by a step depolarization in voltage clamp, there was a proportionality between KNa and INa at all voltages between the threshold of INa and ENa.(More)
Frog neuromuscular junctions were stimulated by different methods to secrete quanta of ACh, and the attendant changes in the ultrastructure of the nerve terminal were assessed by morphometric analysis of electron micrographs. Secretion was stimulated by electrical stimulation at 2 Hz or by application of the secretagogues, lanthanum, ouabain or black widow(More)
Ouabain (0.1 and 0.05 mM) was applied to frog cutaneous pectoris nerve-muscle preparations bathed in modified Ringer's solution containing either 1.8 mM Ca2+ (and 4 mM Mg2+) or no added Ca2+ (4 mM Mg2+ and 1 mM EGTA). During the intense quantal release of acetylcholine (ACh) induced by ouabain, the parameters of the miniature endplate potentials (mepps)(More)
It has been recently shown that frog motoneurons and their nerve terminals contain calcitonin gene-related peptide-like immunoreactivity in large dense-core vesicles (Matteoli et al., Proc. natn. Acad. Sci. U.S.A. 85, 7366-7370, 1988). We report here by an immunofluorescence approach that the same neurons and nerve terminals also contain substance P-like(More)
The regulatory peptide called calcitonin gene-related peptide (CGRP) was detected by immunofluorescence in frog motor neurons and motor nerve terminals. In motor nerve terminals, CGRP-like immunoreactivity was found to be segregated within large dense-core vesicles. To determine whether exocytosis from acetylcholine-containing small synaptic vesicles and(More)
The action of alpha-latrotoxin (alpha-LTx), the major toxic component from black widow spider venom, was studied on mammalian motor nerve endings and fibers. Electrophysiologic recordings of presynaptic and postsynaptic responses at early stages after the application of different doses of alpha-LTx showed massive transient increases in transmitter release(More)
The changes in ionic permeability induced by the application of alpha-latrotoxin to NG108-15 neuroblastoma x glioma cells were examined using the nystatin perforated-patch technique for whole-cell recording. Complex single channel activity appeared in the plasmalemmas after delays that ranged from 1-20 min in Krebs' solution. The conductance of a channel(More)
1. Electrophysiology and morphology have been combined to investigate the time course of the exocytosis of quanta of neurotransmitter induced by elevated concentrations of K+ at the frog neuromuscular junction. 2. Replicas of freeze-fractured resting nerve terminals fixed in the presence of 20 mM-K+ showed images of fusion of synaptic vesicles with the(More)