Erythrocyte lithium transport changes induced by deoxycorticosterone acetate treatment in pigs

Ouabain-insensitive lithium efflux from lithium-loaded pig erythrocytes has sodium-dependent and sodium-independent components. Lithium effluxes into sodium (total efflux) and sodium-free (leak) media, sodium-dependent lithium efflux, defined as the difference between total and leak fluxes, and changes in red cell cation and water contents as well as blood pressure were assessed serially for 3 weeks in pigs implanted with Silastic strips impregnated with deoxycorticosterone acetate or with Silastic alone and maintained on a high salt diet (200 mEq/day). Significant differences developed between the groups in blood pressure, red cell sodium content, red cell water content, leak flux, and sodium-dependent lithium efflux (maximal difference: 648 +/- 60 vs 256 +/- 81 mumoles of lithium per liter of cells per hour, deoxycorticosterone acetate vs controls; p less than 0.01). Increased sodium-dependent lithium efflux paralleled a decrease of the diffusional leak component of lithium efflux; total lithium efflux was unchanged. Deoxycorticosterone acetate hypertension in pigs is a useful model in which to study factors modulating erythrocyte cation content and lithium transport in vivo. Changes in lithium transport characterized in red blood cells in this form of experimental hypertension may reflect generalized membrane phenomena.