Actin filaments regulate voltage-gated ion channels in salamander retinal ganglion cells.
The regulation of voltage-activated K(+), and Ca(2+) currents by actin filaments was studied in salamander retinal ganglion cells, using the whole-cell patch clamp technique and Ca(2+) imaging. Disruption of F-actin by cytochalasin B or latrunculin B resulted in a reduction of L-type Ca(2+) current by 55+/-4%, and a sustained outward K(+) current (I(k)) by 41+/-3%. The effect was diminished when the F-actin stabilizing agent phalloidin was present in the patch pipette. In a group of cells where I(K) exhibited a small degree of inactivation, the effect of F-actin disruption on current was dual; it increased it by 89+/-16%, at -10 mV, and reduced it by 37+/-5% at +50 mV voltage step from the same holding potential of -70 mV. This was accompanied by a shift in a voltage of half-maximal activation toward negative potentials by approximately 20 mV. In Ca(2+) imaging experiments, 30 min incubation of isolated neurons with latrunculin A reduced a depolarization-induced Ca(2+) accumulation by 45+/-5%. These results suggest a role for the actin cytoskeleton in regulating voltage-gated ion channels in retinal ganglion cells.
Schubert
T
T
Department of Neurobiology, University of Oldenburg, Oldenburg, Germany.
Akopian
A
A
D000199:Actins / Q000187:drug effects / Q000378:metabolism*; D000557:Ambystoma / Q000033:anatomy & histology / Q000378:metabolism*; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003571:Cytochalasin B / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D010590:Phalloidine / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D020746:Calcium Channels, L-Type; D024642:Potassium Channels, Voltage-Gated; D013844:Thiazoles; D053778:Thiazolidines; D010590:Phalloidine; D003571:Cytochalasin B; C037068:latrunculin B; D002118:Calcium