Small Capacitance Measurement System in the Patch-Clamp Experiments of the Exocrine Gland Cells.
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概要
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Membrane capacitance measurements are important in studying the mechanisms of exocytosis and endocytosis cycle in the exocrine gland cells. It is expected that the cell membrane capacitance would change during this cycle because of changes of the surface membrane area. A patch clamp system to measure small capacitance changes was studied. 1) A capacitance cancellation circuit was designed to compensate the stray capacitances of the headstage of the patch clamp amplifier and of the electrode. The frequency response of the amplifier had a notched characteristic because of this cancellation circuit and differential amplifier stage. The frequency response was improved by using an operational amplifier with large gain-bandwidth product, and by using specially designed low-pass and high-pass filters. 2) Small capacitance changes of a membrane model were measured with a combined system of a patch clamp amplifier and a two phase lock-in amplifier. It was desired that an access conductance was made large in so far as possible. That made the error of the measurement system less. 3) The measurement system was applied to two different secretory cells, for analysing the responses of exocytosis to intracellular GTP-γS stimulation. In the whole cell configuration of the rat peritoneal mast cells GTP-γS stimulation caused a large increase in membrane capacitance but a small increase in membrane conductance. In the dispersed single acinar cell of mouse pancreas, however, the membrane capacitance change could not be detected because of a large increase in membrane conductance comparing to a near level of access conductance. It is suggested that this capacitance measurement system is applicable to the exocrine gland cells like mouse pancreatic acinar cells only under special conditions where membrane conductance change is reduced or access conductance is very high.
- 一般社団法人 日本生体医工学会の論文
一般社団法人 日本生体医工学会 | 論文
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