Austen E Spruce

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During exocytosis, secretory vesicles of mast cells generate a current transient that marks the opening of the fusion pore, the first aqueous connection that forms between the vesicle lumen and the cell exterior. By recording and analyzing such current transients, we have tracked the conductance of the fusion pore over the first millisecond of its(More)
To enter cells, viruses must fuse their envelope with a host cell membrane. Fusion is mediated by specific, membrane-spanning fusion proteins, of which the influenza virus haemagglutinins (HA) are the best characterized. Several HAs have been sequenced, and the crystal structure of the major part of one HA is known. The conditions for fusion and some of the(More)
Fibroblasts expressing the influenza virus hemagglutinin on their plasma membrane were patch clamped while they fused to erythrocytes. An increase in the fibroblast's membrane capacitance indicated the opening of the "fusion pore," the first aqueous connection between the fusing cells. We show here that the capacitance increase is preceded by a brief(More)
It has been known for some years that skeletal muscle develops a high potassium permeability in conditions that produce rigor, where ATP concentrations are low and intracellular Ca2+ is high. It has seemed natural to attribute this high permeability to K channels that are opened by internal Ca2+, especially as the presence of such channels has been(More)
1. Patch-clamp techniques were used to study adenosine-5'-triphosphate (ATP)-dependent K+ channels in sarcolemmal vesicles from frog skeletal muscle. In addition to its ATP dependence, opening of these channels was voltage dependent, the open-state probability (P open) increasing with depolarization. 2. The reversal potential of unitary currents changed(More)
1. Unitary currents were measured through delayed rectifier potassium channels of frog skeletal muscle, under conditions where either potassium or rubidium ions carried current. 2. Unitary currents were reduced in amplitude when Rb+ was the charge carrier, indicating that Rb+ permeated the channel less readily than did K+. On the other hand permeability(More)
1. Patch-clamp methods were used to study the action of tetraethylammonium ions (TEA+) and other quaternary ammonium ions on adenosine-5'-triphosphate (ATP)-sensitive K+ channels in sarcolemmal vesicles from frog skeletal muscle. The blocking ions were applied either to the external or the internal surface of the membrane patch. 2. External TEA+ caused a(More)
1. We have used single-channel recording to investigate the block by extracellular tetraethylammonium ions (TEA+) of delayed rectifier potassium channels of frog skeletal sarcolemma. 2. TEA+ blocks by reducing the apparent amplitude of unitary currents, without detectable increase in open-level current variance. 3. The block by TEA+ appeared to be 1:1, the(More)
Although the development of several of the voltage-dependent currents in embryonic amphibian myocytes has been described, the overall muscle electrical development, particularly the relative times of expression of different voltage-dependent currents, has not been addressed in a single study under one set of conditions. We have found that, in mesoderm(More)