Erythrocytic Na+ and K+ changes during Babesia bigemina infection in cattle.

The levels of Na+ and K+ in whole blood, plasma and erythrocytes were measured during the course of primary Babesia bigemina infection in cattle. There were significant changes in the levels of Na+ and K+ in erythrocytes, but not in plasma. Erythrocytic Na+ decreased and K+ increased during the course of infection, returning to normal two to three weeks later. Similar ionic changes were produced in animals which were bled to cause packed cell volume depression. It is therefore suggested that the changes in erythrocytic Na+ and K+ levels associated with B bigemina infection result from the anaemia rather than simply the presence of the parasites, and can be attributed to the production of young erythrocytes in which the levels of Na+ and K+ are normally reduced and elevated, respectively. Normal values return with recovery from anaemia and maturation of erythrocytes.