Effect of ouabain and metabolic inhibitors on the Na and K movements and nucleotide contents of L cells.
1. The general characteristics and Na and K movements of L cells (derived from mouse epithelium) have been measured. Both cells grown in suspension (LS cells) and as a monolayer (L cells) were used.2. The volume of L cells was 1.2 x 10(-9) cm(3) and of LS cells 3.5 x 10(-9) cm(3); of this 82% was water.3. Electron micrographs showed the presence of numerous protrusions (filopodia) from both forms of the cell. These had the effect of increasing the surface area of the cell by 2-4 times over smooth cells of the same volume. On changing from the flattened to the spherical shape during trypsinization, the filopodia altered to maintain a constant V/A ratio.4. These cells contain K, about 170 m-mole/l. intracellular water and Na, 9 m-mole/l. intracellular water (L cells only) at 20 degrees C. The K fluxes are 1.9 p-mole/cm(2) sec for LS cells and 0.8 p-mole/cm(2) sec for L cells and the Na fluxes are 1.8 p-mole/cm(2) sec for L cells (expressed as per total cell surface (including filopodia)). If expressed as p-mole/cell per sec then L and LS cells have the same K flux.5. 10(-4)M ouabain reduces the K influx to half, indicating an insensitivity to the glycosides common to the species. In the prolonged presence of ouabain the cells come into a new steady state with a [K](1), of 140 and a [Na](1) of 20-30 m-mole/l. intracellular water, but a constant [Na + K](1).6. Both DNP (10(-3)M) and IAA (10(-4)M) are required for maximum inhibition of K uptake, as both aerobic and anaerobic metabolic pathways may be used to drive the pump.7. K removal decreases the Na efflux, and Na removal (eventually) decreases the K influx providing evidence for Na/K coupling.8. The cells contain 7.5 m-mole/litre intracellular water of ATP, a level some 15 times that of ADP.9. The Na pump in these cells is very similar to that found in other tissues in that (a) it requires K to work, (b) it is blocked by ouabain and metabolic inhibitors and (c) it transports three molecules of Na for each two molecules of K.
D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003864:Depression, Chemical; D004140:Dinitrophenols / Q000494:pharmacology; D006027:Glycosides / Q000494:pharmacology; D007461:Iodoacetates / Q000494:pharmacology; D007739:L Cells / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008854:Microscopy, Electron; D009711:Nucleotides / Q000032:analysis*; D010042:Ouabain / Q000494:pharmacology*; D010100:Oxygen; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D014357:Trypsin
D000227:Adenine Nucleotides; D004140:Dinitrophenols; D006027:Glycosides; D007461:Iodoacetates; D009711:Nucleotides; D010042:Ouabain; D000255:Adenosine Triphosphate; D012964:Sodium; D014357:Trypsin; D011188:Potassium; D010100:Oxygen