Purified bovine rod outer segment disk membranes were attached to a lecithin bilayer membrane. After photoexcitation with a 500-nm flash delivered by a dye laser, a negative photovoltage was observed on the bilayer under normal ionic strengths (100 mM KCl), which had a rise phase of 1-3 ms at 20 degrees C. The photoresponse was obviously due to bleaching of rhodopsin as it decreased for successive flashes of light. It originated most probably during the metarhodopsin-I metarhodopsin-II (meta-I-II) transition of rhodopsin because it was pH dependent at 2 degrees C but not at 20 degrees C. At 10 mM KCl, i.e., under hypotonic conditions, a positive photovoltage with slower kinetics than at high salt was observed. As the disk membranes were merely attached to the bilayer membrane, the photovoltage was apparently due to a light-induced transmembrane potential change in the disk membranes. Possible electrogenic mechanisms underlying the photosignal will be discussed.
展开▼
机译：将纯化的牛杆外段盘膜连接至卵磷脂双层膜。用染料激光器提供的500 nm闪光灯进行光激发后，在正常离子强度（100 mM KCl）下在双层上观察到负光电压，该负离子电压在20摄氏度下具有1-3 ms的上升阶段。光响应为显然是由于视紫红质的漂白，视紫红质随着连续闪光而减少。它最有可能起源于视紫红质的视紫红质-I异视紫红质-II（meta-I-II）转变，因为它在2°C而不是20°C时具有pH依赖性。在10 mM KCl下，即在低渗条件下观察到与高盐时相比动力学慢的正光电压。由于圆盘膜仅附着在双层膜上，因此光电压显然是由于圆盘膜中光诱导的跨膜电势变化所致。将讨论潜在的光信号传导机制。
展开▼
