Showing papers by "Erwin Neher published in 1980"
TL;DR: From the temporal sequence of the pulses, derived estimates of the rates of activation and desensitization of the AChR-channel are derived and it is reported that in the presence of ACh concentrations sufficient to cause desensItization, single channel current pulses appear in groups.
Abstract: High resolution measurements of the current through individual ion channels activated by acetylcholine (AChR-channels) in frog muscle have shown that these currents are discrete pulse-like events with durations of a few milliseconds1,2. Fluctuation and relaxation measurements of end-plate currents have led to the conclusion that the rate of channel opening increases with agonist concentration, and that the channel, once open, closes spontaneously3–6. Katz and Thesleff have shown, however, that in the continued presence of ACh, the initial end-plate current declines to an equilibrium value with a time constant of several seconds7. This reversible phenomenon is referred to as receptor desensitization. We report here that in the presence of ACh concentrations sufficient to cause desensitization, single channel current pulses appear in groups. From the temporal sequence of the pulses, we have derived estimates of the rates of activation and desensitization of the AChR-channel.
577 citations
TL;DR: The first observations of currents through individual Na+ channels under physiological conditions using an improved version of the extracellular patch-clamp technique on cultured rat muscle cells support earlier inferences about channel gating and show a single-channel conductance of approximately 18 pS.
Abstract: The voltage- and time-dependent conductance of membrane Na+ channels is responsible for the propagation of action potentials in nerve and muscle cells. In voltage-step-clamp experiments on neurone preparations containing 104–107 Na+ channels the membrane conductance shows smooth variations in time, but analysis of fluctuations1,2 and other evidence3 suggest that the underlying single-channel conductance changes are stochastic, rapid transitions between ‘closed’ and ‘Open’ states as seen in other channel types. We report here the first observations of currents through individual Na+ channels under physiological conditions using an improved version of the extracellular patch-clamp technique4–6 on cultured rat muscle cells. Our observations support earlier inferences about channel gating and show a single-channel conductance of approximately 18 pS.
413 citations
TL;DR: Ionic currents from individual K+ channels in squid axon membrane have been recorded and the frequency of occurrence of the units increases strongly when the membrane is depolarized.
Abstract: Ionic currents from individual K+ channels in squid axon membrane have been recorded. At hyperpolarizing membrane voltages, unit events occur as widely spaced rectangular pulses with short interruptions. The frequency of occurrence of the units increases strongly when the membrane is depolarized.
211 citations
01 Jan 1980
TL;DR: The neuromuscular junction is the link between nerve and muscle and triggers an action potential, which triggers contraction and thereby initiates contraction.
Abstract: The neuromuscular junction is the link between nerve and muscle. An action potential arriving at the nerve ending liberates a chemical transmitter substance, which diffuses across the synaptic cleft to interact with specific receptors in the postsynaptic membrane. This leads to the opening of ionic channels in this membrane. The resultant conductance increase depolarizes the muscle fiber, which in turn triggers an action potential and thereby initiates contraction (For a review article see Steinbach & Stevens (1976)).