期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：21
页码：6712-6716
DOI：10.1073/pnas.79.21.6712
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The capacitance of the surface membrane of small adrenal chromaffin cells was measured with patch-clamp pipettes. Continuous and discrete changes of capacitance were observed. They were interpreted as changes of surface area connected to exocytotic or endocytotic processes. Most of the measurements were performed in the "whole-cell" recording configuration [Hamill, O. P., Marty, A., Neher, E., Sakmann, B. & Sigworth, F. J. (1981) Pflugers Arch. 391, 85-100], which allows the intracellular Ca2+ concentration to be controlled. With an internal solution highly buffered to low values of Ca2+ concentration (10 nM), the surface capacitance usually decreased and could not be markedly changed by electrical stimulation. At low buffering capacity and medium Ca2+ concentrations (0.1-1 microM), the capacitance measurement showed large fluctuations and discrete steps, reflecting both capacitance decrease and increase. A large transient increase of capacitance could be induced by electrical stimulation under these conditions. It was linked to Ca2+ currents through the membrane. Relatively large (2-6 x 10(-14) F) steps of capacitance decrease were common after extensive stimulation. The size distribution of step-like capacitance changes is well compatible with the idea that steps of capacitance increase reflect individual events of exocytosis of chromaffin granules, whereas steps of the opposite polarity reflect the formation of vesicles or vacuoles by endocytosis.
