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Muscarinic activation of ionic currents measured by a new whole-cell recording method.

Muscarinic activation of ionic currents measured by a new whole-cell recording method. A new method is described as an alternative to whole-cell recording in order to prevent "wash-out" of the muscarinic response to acetylcholine (ACh) in rat lacrimal gland cells. The membrane of a cell-attached patch is permeabilized by nystatin in the patch pipette, thus providing electrical continuity between the pipette and the cytoplasm of the cell without the loss or alteration of cytoplasmic compounds necessary for the maintenance of the response to ACh. With normal whole-cell recording in these cells, the response to ACh, seen as the activation of Ca-activated K and Cl currents, lasts for approximately 5 min. With the nystatin method, the response is not diminished after 1 h. Nystatin, applied extracellularly, is shown to cause a rapid and reversible increase of membrane conductance to cations. In the absence of wash-out, we were able to obtain dose-response curves for the effect of ACh on Ca-activated K currents. An increase of ACh caused an increase in the K current, with apparent saturation at concentrations above approximately 1 microM ACh. The delay between ACh application and the activation of K current was inversely related to ACh and reached a minimum value of 0.7-1.0 s at high ACh. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of General Physiology Rockefeller University Press

Muscarinic activation of ionic currents measured by a new whole-cell recording method.

The Journal of General Physiology , Volume 92 (2): 145 – Aug 1, 1988

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Publisher
Rockefeller University Press
Copyright
© 1988 Rockefeller University Press
ISSN
0022-1295
eISSN
1540-7748
DOI
10.1085/jgp.92.2.145
Publisher site
See Article on Publisher Site

Abstract

A new method is described as an alternative to whole-cell recording in order to prevent "wash-out" of the muscarinic response to acetylcholine (ACh) in rat lacrimal gland cells. The membrane of a cell-attached patch is permeabilized by nystatin in the patch pipette, thus providing electrical continuity between the pipette and the cytoplasm of the cell without the loss or alteration of cytoplasmic compounds necessary for the maintenance of the response to ACh. With normal whole-cell recording in these cells, the response to ACh, seen as the activation of Ca-activated K and Cl currents, lasts for approximately 5 min. With the nystatin method, the response is not diminished after 1 h. Nystatin, applied extracellularly, is shown to cause a rapid and reversible increase of membrane conductance to cations. In the absence of wash-out, we were able to obtain dose-response curves for the effect of ACh on Ca-activated K currents. An increase of ACh caused an increase in the K current, with apparent saturation at concentrations above approximately 1 microM ACh. The delay between ACh application and the activation of K current was inversely related to ACh and reached a minimum value of 0.7-1.0 s at high ACh.

Journal

The Journal of General PhysiologyRockefeller University Press

Published: Aug 1, 1988

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