The actions of internal choline on single "maxi" Ca$ sp{2+}$-activated K$ sp{+}$ channels were studied in excised patches of chromaffin cell membrane. The channels had a unit conductance of approximately 200 pS in a physiological K$ sp{+}$ gradient. / Choline (20-70 mM) applied to the intracellular membrane surface dose dependently reduced outward current flow through the channel. The reduction in single channel current amplitude increased with depolarization. / These data suggest that choline is a fast blocker that binds within the channel pore. The K$ sb{ rm d}$(0) for the reaction is 90 mM while $ delta$ is 0.27, suggesting that the choline binding site senses 27% of the transmembrane electric field. / The average open state probability appeared not to be affected by choline at any of the membrane potentials that were studied.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.60447 |
| Date | January 1990 |
| Creators | Drake, Julie |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Physiology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001214438, proquestno: AAIMM67595, Theses scanned by UMI/ProQuest. |
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