Lysosomes labeled by uptake of extracellular horseradish peroxidase display remarkable changes in shape and cellular distribution when cytoplasmic pH is experimentally altered. Normally, lysosomes in macrophages and fibroblasts cluster around the cell center. However, when the cytoplasmic pH is lowered to approximately pH 6.5 by applying acetate or by various other means, lysosomes promptly mov...

Our objective in this study was to determine the effect of changes in luminal and cytoplasmic pH on cystic fibrosis transmembrane regulator (CFTR) Cl- conductance ( G Cl). We monitored CFTR G Cl in the apical membranes of sweat ducts as reflected by Cl- diffusion potentials ( V Cl) and transepithelial conductance ( G Cl). We found that luminal pH (5.0-8.5) had little effect on the cAMP/ATP-acti...

Short-chain fatty acids, particularly succinic acid, are major metabolic by-products of Bacteroides species. To determine their role as potential virulence factors in infections containing Bacteroides species, short-chain fatty acids were examined for their effect on the neutrophil respiratory burst. Succinate (30 to 50 mM) irreversibly impaired superoxide and hydrogen peroxide production in re...

In the presence of urea, Helicobacter pylori survived for at least 3 h at pH 1. Under these conditions, the cells maintained their cytoplasmic pH at 5.8. De novo protein synthesis during acid shock was not essential for survival of H. pylori at pH 1.

Pressure-damaged Escherichia coli O157 cells were more acid sensitive than native cells and were impaired in pH homeostasis. However differences in acid sensitivity were not related to differences in cytoplasmic pH (pH(i)). Cellular beta-galactosidase was more acid labile in damaged cells. Sensitization to acid may thus involve loss of protective or repair functions.

The effects of platelet-activating factor (PAF) and IL-5 on intracellular pH were investigated in human eosinophils. Purified peripheral blood eosinophils were loaded with the ratiometric fluorescent pH indicator BCECF-AM ester. Stimulation of eosinophils with PAF produced time-dependent alkalinization of the cytoplasm from an initial pH of 7.1+/-0.04 to 7.5+/-0.05. A similar alkalinization res...

The cytoplasmic pH value o f guard cells o f Valerianella locusta was determined from the distribution o f the weak acid [l4C]ABA between the medium and the cell, which was shown to be 8.1 ±0.1. Treatment o f guard cells in media with low pH (pH 5.0) and different concentra­ tions o f sodium acetate (0 -5 m o lm '3) caused a considerable acidification o f the cytoplasm (6 .6-7 .7). Using the co...