title: Effects of photoinduced membrane rigidification on the lysosomal permeability to potassium ions.
abstract: Mechanism for the photoinduced increase in the lysosomal K+ permeability is still unknown. In this study, we investigated the effect of photodamage-induced membrane rigidification on the lysosomal K+ permeability by measuring the membrane potential with bis(3-propyl-5-oxoisoxazol-4-yl)pentamethine oxonol and by monitoring proton leakage with p-nitrophenol. Membrane fluidity was measured by the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene. Methylene blue-mediated photodamage to lysosomes decreased their membrane fluidity and increased their K+ permeability. The photoinduced increase in the K+ permeability can be reversed by fluidizing the rigidified lysosomal membranes with benzyl alcohol. The results suggest that the membrane rigidification induced by photodamage may increase lysosomal K+ permeability. This conclusion is supported by the observation that rigidifying lysosomal membranes by the treatment with membrane rigidifier cholesteryl hemisuccinate also enhanced the lysosomal K+ permeability.
authors.affiliation: Department of Cellular Biophysics, Academia Sinica, Beijing, P. R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhong
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Zheng
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability; D005454:Fluorescence Polarization; D007425:Intracellular Membranes / Q000378:metabolism / Q000528:radiation effects*; D017136:Ion Transport; D008027:Light; D008297:Male; D008560:Membrane Fluidity; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011188:Potassium