CELL CELL CONTACTS ALTER INTRACELLULAR PH

Intracellular pH, an important regulatory factor for many cellular activities, was shown to be modulated by cell adhesion to the solid substratum. In the present work we have shown that cell-cell contacts also affect intracellular pH. pH(i) depends on how many contacts the cell has established with the substratum and the neighboring cells. pH(i) is low in single cells, not contacting each other. It increased with the increase of cell density. pH(i) is again decreased in confluent (topoinhibited) monolayers. pH(i)-shifts triggered by cell-cell contacts seem to be mediated by Na+/H+-antiporter. Dependence of pH(i) on cell density could be simulated by different concentration of Arg-Gly-Asp-which is part of the site of extracellular matrix proteins involved in integrin binding. The dependence of pH(i) on cell-cell contacts is discussed in relation to the phenomena of topoinhibition. © 1992 Academic Press, Inc.