Kinetics and saturation of light-induced near-infrared scattering changes in isolated bovine rod outer segments
Tóm tắt
The axial and radial shrinkage of bovine rod outer segments, monitored by near-infrared scattering changes (P-signal), is investigated in dependence on the intensity of the activating flash. Suspensions of axially oriented and randomly oriented rod outer segments were measured. In the latter case, axial and radial effects are superimposed to another. The following results are obtained:
The signals from the isotropic sample are fitted by a phenomenological model. It introduces three first order processes concatenated in series; the first step is assumed as a rhodopsin transition inducing the two further processes. The distortion of the signals with increasingϱ is then described assuming aϱ-dependent quenching of this induction, according to the measured amplitude saturation. The time constants remain thereby unchanged. The fit yields the values ln 2/k=4, 11, and 45 ms with mean square deviations of 20%.
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