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Stimulation by serum of the Na + /H + antiporter in quiescent pig kidney epithelial (LLC‐PK 1 ) cells and role of the antiporter in the reinitiation of DNA synthesis
Author(s) -
Haggerty John G.,
Agarwal Neeraj,
Amsler Kurt,
Slayman Carolyn W.,
Adelberg Edward A.
Publication year - 1987
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041320125
Subject(s) - antiporter , bicarbonate , dna synthesis , amiloride , thymidine , stimulation , sodium–hydrogen antiporter , chemistry , biology , microbiology and biotechnology , medicine , sodium , biochemistry , endocrinology , dna , membrane , organic chemistry
LLC‐PK 1 cells can be brought into a classical quiescent state by depriving them of serum for 6 days. At this time, pulse‐labeling with [ 3 H]‐thymidine shows that only 3% of the cells are synthesizing DNA, but the quiescent cells can be stimulated with serum to re‐enter the cell cycle at a point early in G 1 . The rate of amiloride‐sensitive 22 Na + uptake (as a measure of the Na + /H + antiporter) is relatively low during quiescence; it rises 2‐ to 3‐fold within 4 h after serum addition. This increase in antiporter activity appears to be required for the resumption of DNA synthesis in the absence of bicarbonate, because ethylisopropylamiloride (EIPA) blocks [ 3 H]‐thymidine incorporation when serum is added to cells in bicarbonate‐free medium. In the presence of bicarbonate, however, EIPA has no effect on [ 3 H]‐thymidine incorporation, indicating that another (bicarbonate‐dependent) transport system can substitute for the antiporter under these conditions.