Precipitation within unilamellar vesicles. Part 2. Membrane control of ion transport
Mann S., Kime MJ., Ratcliffe RG., Williams RJP.
Phosphorus-31 and < sup > 1 < /sup > H n.m.r. spectroscopy have been used to investigate the control of intravesicular pH (pH < inf > in < /inf > ) by lipid membranes. The presence of encapsulated permeable anions is crucial in the intravesicular precipitation of hydroxides and oxides. In the absence of permeable anions no change in pH < inf > in < /inf > has been observed on increasing extravesicular pH (pH < inf > out < /inf > ) above 12.0. In the presence of permeable NO < inf > 3 < /inf > < sup > - < /sup > ions, pH < inf > in < /inf > rises only when pH < inf > out < /inf > is increased above a value of 11.0. These observations are described in terms of the Goldman-Katz-Hodgkin equation for ion fluxes across a membrane permeable to more than one ion.