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Acetylcholine-induced membrane potential oscillations in the intact lens
G R Thomas1, G Duncan, J Sanderson
1Department of Cell Biology and Physiology, School of Biological Sciences, University of East Anglia, Norwich, United Kingdom.
Investigative Ophthalmology & Visual Science
|January 16, 1998
Summary
Acetylcholine activates muscarinic receptors in rabbit lenses, altering electrical properties and causing membrane potential oscillations. Calcium influx, not intracellular stores, drives this oscillatory response, offering insights into lens physiology.
Area of Science:
- Ophthalmology
- Neuroscience
- Cell Physiology
Background:
- Acetylcholine signaling is implicated in cataract formation.
- Understanding the lens's electrical response to acetylcholine is crucial.
Purpose of the Study:
- To investigate the electrical response of the intact rabbit lens to acetylcholine.
- To elucidate the role of acetylcholine in modulating lens electrical activity.
Main Methods:
- Utilized a two-internal-microelectrode technique to monitor membrane potential (Vm) and electrical conductance (Gm).
- Studied isolated, perifused rabbit lenses.
- Applied acetylcholine, atropine, thapsigargin, cyclopiazonic acid, and nifedipine.
Main Results:
- Acetylcholine (100 nM to 1 mM) decreased lens membrane conductance and depolarized membrane potential.
- Responses were antagonized by atropine (1 microM to 100 microM).
- Sustained membrane potential oscillations occurred in 34% of lenses upon prolonged acetylcholine exposure, dependent on Ca2+ influx and blocked by nifedipine.
Conclusions:
- Rabbit lenses possess muscarinic receptors that modulate ionic conductances upon activation.
- Acetylcholine induces membrane potential oscillations in the lens, primarily driven by Ca2+ influx.
- These findings contribute to understanding lens electrophysiology and potential mechanisms in cataract development.
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