Renal epithelial cell growth can occur in absence of Na+-H+ exchanger activity

Journal Article · Sun Nov 01 04:00:00 EST 1987 · Am. J. Physiol.; (United States)

OSTI ID:5653644

Mohrmann, M; Cantiello, H F; Ausiello, D A

An electroneutral Na+-H+ exchange system has been described in a variety of tissues and cell types, including those of renal origin, and has been proposed to play a role in the activation of growth. We have recently characterized the presence of this ubiquitous transporter in the apical domain of confluent epithelial LLC-PK1 cells. Because most apical membrane proteins appear late in cell growth, accompanying epithelial cell polarization, we determined whether the Na+-H+ exchanger is required for the growth of LLC-PK1 cells. The studies reported here show that there is no obligatory requirement for increased H+ efflux or Na+ entry via the Na+-H+ exchanger for the initiation of cell growth in this epithelial cell line. We used /sup 22/Na+ influx, acid extrusion, and intracellular pH determinations to show that onset of cell growth, as measured by DNA content, precedes the activity of the Na+-H+ exchanger in exponentially growing cells, whereas confluent monolayers express Na+-H+ exchanger activity. When confluent cells are replated at low density, Na+-H+ exchanger activity disappears within 8 h in contrast to high-density replated cells. The fact that Na+-H+ exchanger activity is only present in confluent monolayers suggests that the development of tight junctions and polar differentiation play a role in the expression of the Na+-H+ exchanger and that this exchanger is more important to the polar epithelial cell for transepithelial transport than for the maintenance of intracellular pH.

• Research Organization: Massachusetts General Hospital, Boston
• OSTI ID: 5653644
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 253; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMAL CELLS
ANIMAL TISSUES
BARYONS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
CELL MEMBRANES
DNA
ELEMENTARY PARTICLES
EPITHELIUM
FERMIONS
GROWTH
GROWTH FACTORS
HADRONS
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
LIGHT NUCLEI
MEMBRANE TRANSPORT
MEMBRANES
MITOGENS
NUCLEI
NUCLEIC ACIDS
NUCLEONS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
PROTONS
RADIOISOTOPES
SODIUM 22
SODIUM COMPOUNDS
SODIUM ISOTOPES
TISSUES
TRACER TECHNIQUES
YEARS LIVING RADIOISOTOPES