
%0 Journal Article
%A Henry, RJ 
%A Schibeci, A 
%A Stone, BA 
%T Proton Motive Potential Difference Across the Plasma Membrane of Plant Cells: a Comparison of Cultured Cells and Protoplasts From Italian Ryegrass (<I>Lolium multiflorum</I> Lam.) Endosperm
%J Functional Plant Biology
%D 1984/06/01
%V 11
%N 3
%P 119-128
%K 
%R https://doi.org/10.1071/PP9840119
%U https://www.publish.csiro.au/paper/PP9840119 
%X The electrochemical proton gradient (&#916;&#956;H+) was measured across the plasma membranes of ryegrass (Lolium multiflorum Lam.) endosperm cells grown in suspension culture. The pH gradient (&#916;pH) and the transmembrane electrical potential (&#916;&#936;) of cells and protoplasts were compared. The pH gradient (&#916;pH) was measured from the distribution of acetylsalicylic acid and 5,5-dimethyloxazolidine and the membrane potential (&#916;&#936;) was calculated from the distribution of the lipophilic tetraphenylphosphonium cation (TPP+) between the cells and medium. The protoplasts and cells maintained a similar &#916;pH. At the external pH of the growth medium (pH 5.5), the cytoplasmic pH was about 7. Under these conditions the &#916;&#936; was -60 mV (negative inside) for cells and -46 mV for protoplasts. &#916;pH and &#916;&#936; have values which vary reciprocally depending on the external pH. The main contributor to &#916;&#956;H+ at pH 4.0 is &#916;pH whereas, at pH 7.0, &#916;&#936; is the main component. The external K+ concentration influences the cytoplasmic pH significantly only at the higher external pH values. 
