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Lanthanum‐Induced alterations in cellular electrolytes and membrane potential in ehrlich ascites tumor cells
Author(s) -
Levinson Charles,
Mikiten Terry M.,
Smith Thomas C.
Publication year - 1972
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.1040790215
Subject(s) - pronase , membrane , biophysics , chemistry , membrane potential , cell membrane , biochemistry , biology , trypsin , enzyme
We have investigated the effect of varying La +3 concentrations (0.01 mM to 2.0 mM) on membrane potential and electrolyte composition of Ehrlich ascites tumor cells. La +3 concentrations less than 0.02 mM had no effect. Above 0.02 mM, La +3 induced concentration‐dependent loss of electrolytes and water from the cells. At 1.0 mM the effect was maximal and resulted in an 87% reduction in cellular K + , 79% in Cl − and 21% in Na + within 4.8 minutes. The Na + loss occurred even in the face of an electrochemical potential gradient favoring Na + entry. La +3 increased the recorded values of membrane potential; the magnitude of the effect was related to the external La +3 concentration, and was maximal at 1.0 mM. Studies using 140 La showed that La +3 binds rapidly to the cell surface and does not enter the cells. The amount of La +3 bound to the cells was related to the external La +3 concentration by a sigmoidal curve and was maximal at about 1.0 mM. The bound La +3 could not be displaced by either added La +3 or Ca +2 . Agents known to effect the integrity of the cell membrane, such as phospholipase C, neuraminidase, pronase and Hg +2 were tested for their ability to displace bound La +3 . Only pronase displaced bound La +3 , indicating that La +3 associates with cell protein. It is hypothesized that La +3 rapidly interacts with membrane protein causing alterations in membrane permeability and capacity to actively transport ions.