[Kinetics of work of ion channels operated by nicotinic cholinoreceptors in the membrane of mollusk neurons].
The patch-clamp technique in cell-attached configuration was applied to investigate suberyldicholine-induced currents in Planorbarius corneus neurons. The single channels currents registered as inward ones at hyperpolarization of the patches were due to chloride ions efflux from the cell. Suberyldicholine (5 mumol/l) was added into the patch electrode. Usually there were more than one channel in the membrane fragment under the clamp control. The open and closed times, bursts and clusters' lengths were measured and histograms of single-channel parameters were obtained. Histograms were approximated by a sum of exponentials. Single exponentials were fitted to open times; to = 27 +/- 3 ms (n = 21). Histograms of closed times were fitted by three exponentials: tc1 = 9.5 +/- 1.0 ms (n = 21)--short gaps; tc2 = 171 +/- 33 ms (n = 19)--intermediate gaps: tc3 = 5.2 +/- 1.0 s (n = 21)--long gaps. The openings were grouped in bursts: tb2 = 203 +/- 23 ms (n = 10) and in clusters of bursts: tk3 = 1.5 +/- 0.5 s (n = 9). There were some evidences that the single burst was the result of opening, closing and reopening of just the same channel. A kinetic model with one open and three nonconducting states is plausible for single-channel data. Two long-lasting closed times may be associated with desensitization states of the receptor-channel complex. Estimates of the kinetic model parameters were obtained, that may be useful in the further study of a mode of action for cholinergic drugs in Planorbarius corneus neurons.
Kachman
A N
AN
Frolova
E V
EV
Gapon
S A
SA
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008974:Mollusca / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000502:physiology*
D007473:Ion Channels; D011978:Receptors, Nicotinic
Kinetika raboty ionnykh kanalov upravliaemykh nikotinovymi kholinoretseptorami v membrane neĭronov molliuska.