[Fast photo-induced changes in the light scattering of vertebrate photoreceptor membrane preparations. Study of a suspension of retinal outer rod segments].

It has been found that light induced a fast decrease of light scattering of suspensions of retinal rod outer segments. This decrease coincides in time with the decay of metarhodopsin I. Evidence is presented that this effect is conditioned by an increase of the interdisc volume due to a photoinduced increase of ion numbers in them. The value of the effect was practically independent of pH, ionic composition and osmomolarity of the medium. The effect amplitude was small (10% to the value of light scattering change induced by hypertonic shock) and in proportion to the value of bleached rhodopsin. Calculations in the basis of these data have shown that bleaching of a rhodopsin molecule brings about the appearance of no more than one ion in the interdisc volume. The results obtained are used to analyzed the validity of our proposition concerning the existence of ionic photoconductivity in the disc membranes of rod outer segments.