Imaging stochastic spatial variability of active channel clusters during excitation of single neurons.
Topographical maps of membrane voltages were obtained during action potentials by imaging, at 1 microm resolution, live dissociated neurons stained with the voltage sensitive dye RH237. We demonstrate with a theoretical approach that the spatial patterns in the images result from the distribution of net positive charges condensed in the inner sites of the membrane where clusters of open ionic channels are located. We observed that, in our biological images, this spatial distribution of open channels varies randomly from trial to trial while the action potentials recorded by the microelectrode display similar amplitudes and time-courses. The random differences in size and intensity of the spatial patterns in the images are best evidenced when the time of observation coincides with the duration of single action potentials. This spatial variability is explained by the fact that only part of the channel population generates an action potential and that different channels open in turn in different trials due to their stochastic operation. Such spatial flicker modifies the direction of lateral current along the neuronal membrane and may have important consequences on the intrinsic processing capabilities of the neuron.
Savtchenko
L P
LP
International Center for Molecular Physiology (Dniepropetrovsk division), National Academy of Sciences of Ukraine, Research Laboratory of Biophysics and Bioeletronics, Dniepropetrovsk State University, Dniepropetrovsk 49050, Ukraine.
Gogan
P
P
Korogod
S M
SM
Tyc-Dumont
S
S
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D002478:Cells, Cultured; D004558:Electric Stimulation; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D007091:Image Processing, Computer-Assisted; D008839:Microelectrodes; D018715:Microscopy, Video; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D009620:Nodose Ganglion / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D011726:Pyridinium Compounds / Q000493:pharmacokinetics; D051381:Rats; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*
D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D015222:Sodium Channels; C048153:4-(6-(4-dibutylaminophenyl)-1,3,5-hexatrienyl)-1-(4'-sulfobutyl)pyridinium