Lanthanum-Induced alterations in cellular electrolytes and membrane potential in ehrlich ascites tumor cells

✍ Scribed by Charles Levinson; Terry M. Mikiten; Thomas C. Smith

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 736 KB
• Volume: 79
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040790215

✦ Synopsis

Abstract

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.