Ramped voltage clamp studies of cholinergic responses in Helix aspersa neurones
Ramped voltage clamp studies of cholinergic responses in Helix aspersa neurones
The responses of Helix aspersa neurones to acetylcholine ware observed using a Ramped Voltage Clamp technique. This provided a rapid means of studying the ionic involvements and conductance changes.The effects of altered external ionic concentrations on the acetylcholine responses were tested. Three cell types were observed, distinguished by differing ionic involvements in the conductance changes induced by acetylcholine. Acetylcholine acted in three different ways: (a) Increased chloride ion conductance causing a hyperpolarising outward current (H); (b) Increased sodium ion conductance causing a depolarising inward current (D); (c) Increased membrane conductance to both sodium and chloride ions, usually causing a depolarising inward current overall but occasionally a hyperpolarising outward current (D (f C1) ). Hexamethonium discriminated between the responses, only blocking the increased sodium ion conductance but not affecting the increased chloride ion conductance. Decamethonium acted as an agonist producing only increased chloride ion conductance on cells where acetylcholine increased chloride ion conductance. At higher doses it acted as an antagonist of the increased sodium ion conductance. d-Tubocurarine and strychnine were antagonists of the acetylcholine responses mediated by increased membrane conductance to chloride or sodium ions. There appeared to be two receptors mediating two different, independent conductance increases to specific ions. These receptors were present separately or together on the three cell types.
University of Southampton
1978
Chad, John Edward
(1978)
Ramped voltage clamp studies of cholinergic responses in Helix aspersa neurones.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The responses of Helix aspersa neurones to acetylcholine ware observed using a Ramped Voltage Clamp technique. This provided a rapid means of studying the ionic involvements and conductance changes.The effects of altered external ionic concentrations on the acetylcholine responses were tested. Three cell types were observed, distinguished by differing ionic involvements in the conductance changes induced by acetylcholine. Acetylcholine acted in three different ways: (a) Increased chloride ion conductance causing a hyperpolarising outward current (H); (b) Increased sodium ion conductance causing a depolarising inward current (D); (c) Increased membrane conductance to both sodium and chloride ions, usually causing a depolarising inward current overall but occasionally a hyperpolarising outward current (D (f C1) ). Hexamethonium discriminated between the responses, only blocking the increased sodium ion conductance but not affecting the increased chloride ion conductance. Decamethonium acted as an agonist producing only increased chloride ion conductance on cells where acetylcholine increased chloride ion conductance. At higher doses it acted as an antagonist of the increased sodium ion conductance. d-Tubocurarine and strychnine were antagonists of the acetylcholine responses mediated by increased membrane conductance to chloride or sodium ions. There appeared to be two receptors mediating two different, independent conductance increases to specific ions. These receptors were present separately or together on the three cell types.
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Published date: 1978
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Local EPrints ID: 458825
URI: http://eprints.soton.ac.uk/id/eprint/458825
PURE UUID: d17db625-cca2-4ce0-9b4c-f5c64c55edc3
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Date deposited: 04 Jul 2022 16:56
Last modified: 04 Jul 2022 16:56
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Author:
John Edward Chad
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