FORMATION OF MEMBRANE NETWORK STRUCTURES UPON CHLOROPLAST ENERGIZATION IN THE PRESENCE OF LOCAL-ANESTHETICS

An electron-microscopic study of the ultrastructure of pea chloroplast s in the presence of permeant lipophilic amines (dibucaine and tetraca ine) was conducted. Under continuous illumination, 25 mu M dibucaine o r 50 mu M tetracaine, inhibiting ATP synthesis by 40% or less, bring a bout specific chloroplast ultrastructural changes which are reversible in the dark. The main effect produced by these agents is the formatio n of network-like structures in the intergranal space of the chloropla st. They are composed of numerous anastomoses between the membranes of agranal lamellae and marginal granal (stroma-exposed) thylakoids. The anastomoses consist of contacting double membranes arranged perpendic ularly to the thylakoid plane. In addition, local changes in the membr anes (creases and narrow peaks) occur, which are partially retained 2 min after switching off the light, possibly reflecting the process of anastomosis formation/destruction.