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Two methods are described for estimation of passive cell parameters such as membrane capacitance, membrane conductance and access resistance in tight-seal whole cell recording. Both methods are restricted in their application to cases where the cell under study can be approximated by a simple three-component network with linear properties over some voltage(More)
In mast cells and granulocytes, exocytosis starts with the formation of a fusion pore. It has been suggested that neurotransmitters may be released through such a narrow pore without full fusion. However, owing to the small size of the secretory vesicles containing neurotransmitter, the properties of the fusion pore formed during Ca2+-dependent exocytosis(More)
Exocytosis, the fusion of secretory vesicles with the plasma membrane to allow release of the contents of the vesicles into the extracellular environment, and endocytosis, the internalization of these vesicles to allow another round of secretion, are coupled. It is, however, uncertain whether exocytosis and endocytosis are tightly coupled, such that(More)
The ionic conductances in rat basophilic leukemia cells (RBL-2H3) and rat peritoneal mast cells were investigated using the patch-clamp technique. These two cell types were found to have different electrophysiological properties in the resting state. The only significant conductance of RBL-2H3 cells was a K+-selective inward rectifier. The single channel(More)
Several proteins involved in exocytosis have been identified recently, but it is still completely unclear which molecules perform the fusion event itself. Although in viral fusion the fusion proteins are known, even there the molecular mechanism remains controversial. Investigation of single fusion events by electrophysiological techniques together with(More)
We have investigated the granule fusion events during exocytosis in horse eosinophils by time-resolved patch-clamp capacitance measurements. Stimulation with intracellular GTP gamma S leads to a stepwise capacitance increase by 4.0 +/- 0.9 pF. At GTP gamma S concentrations < 20 microM the step size distribution is in agreement with the granule size(More)
We investigated the noise levels in cell-attached patch capacitance recordings with a lock-in amplifier. The capacitance noise level decreases with increasing sine wave frequency up to 20-40 kHz. With a 20-mV rms sine wave the rms noise level above 8 kHz is <50 aF. With increasing sine wave amplitudes a further reduction down to 14 aF could be achieved.(More)
We have investigated the ATP-induced permeabilization of rat peritoneal mast cells using three different techniques: (a) by measuring uptake of fluorescent membrane and DNA marker dyes, (b) by voltage-clamp measurements using the patch-clamp technique, and (c) by measurements of exocytosis in response to entry of Ca2+ and GTP gamma S into permeabilized(More)
An increase in free Ca2+ triggers exocytosis in pituitary nerve terminals leading to an increase in membrane area and membrane capacitance. When Ca2+ is increased by step depolarization, an instantaneous capacitance increase during the first 80 ms is followed by a slow increase extending over several seconds. We measured capacitance changes associated with(More)