Voltage clamp analysis of acetylcholine receptor desensitization in isolated mollusc neurones

Abstract

1. Desensitization produced by acetylcholine (ACh) in completely isolated Limnaea stagnalis neurones with chloride-selective membrane channels was studied using a voltage-clamp technique. 2. A difference in the time course of the neurone responses to ACh, depending on whether the measured parameter was voltage or current, was observed and explained on the basis of an equivalent electric scheme of the neurone soma membrane. 3. Desensitization onset was shown not to depend on membrane potential in the range of -30 to -120 mV. 4. Variation of external Ca2+, Na+ and Cl- concentrations over a wide range had little influence on the onset of desensitization and recovery from it. 5. An obvious difference is shown to exist between features of desensitization in mollusc neurone and frog muscle end-plate ACh receptors.