ИСТИНА

Theoretical analysis based on an original kinetic model has revealed that a depression sensitivity to acetylcholine in Helix neurons in cellular correlate of habituation depends not only on exocytosis and endocytosis, but also on the lateral diffusion of Ach­receptors. Lateral diffusion of Ach­receptors under experimental conditions was assessed by applying electrophysiological methods. The following drugs were used: MbCD (depletes cholesterol in the cell membrane), Ro 48­8071 (cholesterol synthesis inhibitor), antibodies spectrin and merlin (against actin­binding proteins). In the presence of MbCD (1 мМ) and Ro 48­8071 (2 мкМ) the rate of Ach­induced current depression was slower. The steady- state level of peak current was achieved in case of MbCD, but not of Ro 48­8071. In the presence of antibodies speсtrin (1:100) and merlin (1:50) the rate of Ach­induced current depression was faster and recovery of peak current was reduced. Fitting a kinetic model to electrophysiological data shown that MbCD causes a decrease the diffusion rate and constants of endocytosis and exocytosis. Whereas antibodies causes an increase of the diffusion rate and constants of endo ­ and exocytosis. These results indicate that lateral diffusion of Ach­receptors participates during depression of Ach­induced current in the cellular correlate of habituation.