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1. End-plate potentials (e.p.p.s) and end-plate currents (e.p.c.s) were recorded intracellularly from muscle fibres of frog and mouse at various levels of curarization to determine the relation between the potential change and the underlying synaptic conductance change over a wide range of e.p.p. amplitudes. 2. In frog muscle fibres the e.p.p.-e.p.c.(More)
1. Patch-clamp techniques were used to study the properties of a Na+-activated K+ current (IK(Na) in neurones cultured from embryonic chick brain stem. 2. With whole-cell clamp, a depolarizing voltage command evoked an inward current that was followed by an outward current with two components, the first transient, the second sustained. 3. Tetrodotoxin (TTX,(More)
1. Isolated cell clusters from ciliary ganglia of 3- to 4-day-old chickens were used to examine the electrical characteristics and sensitivity to iontophoretically applied acetylcholine (ACh) of normal cells and cells that had been axotomized on the day of hatching. 2. Resting potentials, input resistances and capacitances were the same in axotomized cells(More)
Previous experiments on cholinergic synapses in chick cochlear hair cells have shown that calcium entering through acetylcholine-activated synaptic channels in turn activates calcium-dependent potassium currents, resulting in synaptic inhibition. In voltage-clamp experiments such currents would be expected to increase with depolarization (as the driving(More)
1. The relation between presynaptic depolarization and transmitter release was examined at a synapse between a Müller axon and a lateral interneurone in the spinal cord of the lamprey. Two micro-electrodes, one for passing current and the other for recording the resulting voltage change, were placed in the presynaptic axon; a single electrode for recording(More)
Previously, suggestions have been made that postjunctional folds at the vertebrate motor end plate might, in some way, serve to enhance neuromuscular transmission. This suggestion was examined quantitatively using a model junction with geometry similar to that seen in mammalian 'fast twitch' muscles. It was found that the depolarization produced at the top(More)
Voltage-clamp techniques were used to measure fluctuations in membrane current produced by the application of glycine to Müller cells in the brain stem of the lamprey. The power density spectrum of the glycine-induced current 'noise' was consistent with the hypothesis that glycine activated a single population of conductance channels with open times(More)
Learned helplessness (LH) consists of shock escape deficits evidenced by animals previously exposed to inescapable shock. This phenomenon has shown promise as a behavioral screen for new antidepressant drugs. Unfortunately, some stocks of rats evidence low susceptibility to LH training. Accordingly, male rats from 8 different stocks were tested for(More)
Microbial populations stochastically generate variants with strikingly different properties, such as virulence or avirulence and antibiotic tolerance or sensitivity. Photorhabdus luminescens bacteria have a variable life history in which they alternate between pathogens to a wide variety of insects and mutualists to their specific host nematodes. Here, we(More)