抄録
Frog urinary bladders were fixed in a distended position and filipin was added to (A) both serosal and mucosal sides, (B) only serosal side, or (C) only mucosal side of the bladder, or to (D) scraped mucosal cells. Incubation was carried out from 30 min to 18 hr at room temperature.
In (A), filipin-sterol complexes were found in the apical cell membrane (AM) and the apical granule membrane (GM), but not in the basolateral cell membrane (BLM) at 30 min of incubation. On the contrary, in (B) at 15 hr, the complexes were found in BLM and GM, but not in AM. In (C) at 15 hr and in (D) at 2 hr, the complexes were found all in AM, GM and BLM. When the penetration of filipin seemed marginal in (A) and (B), ridges of 17 nm width on the P face and corresponding ditches on the E face were seen in GM and some protuberances and pits were found at the crossings of ridges and ditches.
The present results showed clearly that filipin penetrates very slowly and the filipin-sterol complexes may be formed nonuniformly even in adjacent membranes. The ridges and ditches might show a preliminary stage of the complex formation in GM.
