The effect of anti-L on ouabain binding to sheep erythrocytes.
Binding of 3H-ouabain was studied in high potassium (HK) and low potassium (LK) sheep red cells. In particular, we investigated the effect of anti-L, an antibody raised in HK sheep against L-positive LK sheep red cells, on 3H-oubain binding and its relation to K+ -pump flux inhibition in LK cells. HK cells were found to have about twice as many 3H-ouabain binding sites and a higher association rate for 3H-ouabain than homozygous LL-type LK cells. The number of 3H-ouabain molecules bound to heterozygous LM-type LK cells is lower than that on LL cells, but the rate of ouabain binding is between that of HK and LL red cells. A close correlation was observed between the rates of 3H-oubain binding and fraction K+-pump inhibition. Exposure of LM and LL cells to anti-L did not affect the number of 3H-ouabain molecules bound at saturation, but increased the rates of glycoside binding and K+ -pump inhibition proportionately, so that for LK cells in the presence of anti-L, the rates of the two processes approximate those of HK cells. These data exclude the possibility that anti-L generates entirely new pump sites in LK sheep cells, but suggest that the antibody increases the affinity of the existing -a+ -K+ pumps for the glycoside.
D000818:Animals; D000906:Antibodies; D001666:Binding Sites, Antibody; D001693:Biological Transport, Active; D004912:Erythrocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D007700:Kinetics; D010042:Ouabain / Q000097:blood*; D011188:Potassium / Q000097:blood / Q000494:pharmacology; D011955:Receptors, Drug / Q000187:drug effects; D012756:Sheep / Q000276:immunology
D000906:Antibodies; D011955:Receptors, Drug; D010042:Ouabain; D011188:Potassium