Light-Induced Conductance Changes in Rod Outer Segments
Alternating current measurements have been made on packed suspensions of rod outer segments. Since it is suspected that any changes that occur in the passive electrical properties of this experimental material will have their origin in conductive (i.e. dissipative) elements, attention has been directed to the detection of changes in the real part of admittance (Δ G) representing the change in amplitude of current through the material inphase with an applied sinusoidal voltage of unit amplitude). Owing to the presence of capacitative elements arising from membranes, Δ G will, in general, vary with the frequency of the applied voltage. Information can thus be derived about the position, relative to known structural features, of conductive elements that change on illumination. In particular, an increase of Δ G with frequency may be an indication that one is probing beyond the surface membrane to observe changes taking place in the interior of rod outer segments.
KeywordsPermeability Sucrose Albumin EDTA Platinum
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