AJP - Cell Physiology, Vol 259, Issue 2 C205-C214, Copyright © 1990 by American Physiological Society
Distribution of F-actin in bipolar and horizontal cells of bass retinas
D. K. Vaughan and E. M. Lasater
Department of Physiology, University of Utah School of Medicine, Salt Lake City 84108.
F-actin distribution was studied in bipolar and horizontal interneurons of
white bass retina. Cryosections of intact retina and isolated cells in
culture were labeled with the F-actin specific probe fluorescent
phalloidin. In intact retina, labeling was heaviest in the
photoreceptor-pigment epithelium region, outer limiting membrane,
horizontal cell somata, and plexiform layers. In isolated bipolar and
horizontal cells, labeling patterns specific to each cell type were
obtained, as were patterns in distinct categories of neurites extending
from cells maintained in culture for several days. Label was especially
heavy where contacting horizontal cells apposed and were coupled via
extensive gap junctions both in the intact retina and in culture. This
observation led to the hypothesis that this F-actin domain might modulate
junctional conductance. However, cytochalasin D-induced disruption of the
F-actin cytoskeletons of coupled, cultured horizontal cells had no effect
on normal coupling or on dopamine-induced uncoupling. The F-actin domain
may instead mediate gap junction turnover.
