Journal of Neuroscience, Vol 7, 3072-3080, Copyright © 1987 by Society for Neuroscience
Voltage-activated potassium channels in the plasma membrane of rod outer segments: a possible effect of enzymatic cell dissociation
S Hestrin and JI Korenbrot
Department of Physiology, University of California, School of Medicine, San Francisco 94143.
Using patch-clamp techniques, we recorded single-channel currents from the
plasma membrane of the outer segment of isolated light-adapted rods. The
channels are potassium-selective and their conductance is about 87 pS. The
channels are activated by depolarization and are not sensitive to
cytoplasmic calcium, they are exclusively found in rods isolated with the
proteolytic enzyme papain, and are not detected in rods isolated by
mechanical means. Thus, these channels do not exist in an activatable form
in the outer segment plasma membrane under physiological conditions. The
channels might be derived from a normally inaccessible structure, such as
the disk membrane, or, alternatively, they might be a modified form of a
channel that is not active in the intact rod.