Figure 7. Steady rhodopsin gradient in amphibian ROSs persists while retinaloxime equilibrates quickly and completely. A: Initial dark absorbance spectra recorded at two sides of a salamander ROS in standard Ringer pH 7.5+50 mM hydroxylamine show even distribution of rhodopsin. B: Absorbance changes at bleached and unbleached sides of the ROS at 370 nm and L-polarization trace formation and subsequent equilibration of retinaloxime. C, D show T- and L-absorbance spectra at two sides of ROS after 10 min postbleach. Smooth lines are visual pigment template fits to long-wave peaks of postbleach absorbance spectra. They show grossly nonequilibrium distribution of rhodopsin. Noisy curves were obtained by subtracting template curves from the postbleach spectra. Retinaloxime peaks at approximately 370 nm were equilibrated, pointing to the structural continuity of the disc membrane.