Isolation of components of admittance change in rod outer segments

1. Rods were separated by equilibration on a bovine serum albumin (BSA) density gradient into two major fractions, differing in their response to light.2. In one fraction the response, measured as a change in the real part of admittance DeltaG, appeared to consist exclusively of component I, while in the other, component II was prominent.3. Evidence is presented that component I arose in damaged rods. This follows from observations on rods which have been deliberately damaged by freezing followed by thawing, or by fragmentation.4. In such damaged rods, component II was absent while component I was increased in amplitude.5. The frequency dependence of component I in isolation was characterized as a positive DeltaG of constant amplitude from low frequencies up to the characteristic frequency f(Y) for the major dispersion of admittance. Above this frequency, it declined to a variable extent.6. The frequency dependence of component II observed in isolation was consistent with the previous analysis.7. A negative-going DeltaG is described which was linear with the amount of rhodopsin bleached and which was frequency independent up to the highest frequency of measurement (17 MHz).8. The origins of component I and the negative component are discussed.