Red blood cell membrane cation transport in normotensive psoriatics

Psoriasis might be a widespread membrane disorder. To verify whether under the influence of psoriasis the red cell membrane cation metabolism is altered, we compared 46 psoriatics with 23 normotensive controls. A significant increase was observed in intracellular K+ content, in the maximal velocity of the Na(+)-K+ ATPase, of the Na(+)-K(+)-Cl- outward co-transport, of the Na+/H+ exchange, as well as in the outward passive permeability for Na+. No difference was seen between the two groups in Na+ content, Li+/Na+ exchange or in the passive permeability to K+. In 8 psoriatics treated with etretinate (10-75 mg/day for 1-36 months), Na(+)-K+ ATPase, Na(+)-K(+)-Cl- co-transport and the passive permeability for Na+ were not significantly different from controls. These results suggest that the primary abnormality might be an increased Na+ influx, in part through the Na+/H+ exchange, which is compensated by increased activity of outward transports, and confirm that the red cells are a useful model for the study of membrane transport in this disease. Our results indicate also that these membrane transport abnormalities can be corrected by etretinate treatment.