Effect of rHuEPO on the sympathetic activity and alpha(2)-adrenoceptors inhemodialysis patients

This study was undertaken to evaluate the effect of recombinant human eryth ropoietin (rHuEPO) given for correction of renal anemia, on the sympathetic function in hemodialyzed patients. Blood pressure, plasma catecholamine le vels and platelet alpha(2)-adrenoceptor density were measured in 9 hemodial yzed patients before and after three months on rHuEPO therapy. Plasma catec holamines were measured by a radioenzymatic assay, alpha(2)-adrenoceptor ch aracteristics were measured in intact platelets by radioligand binding assa y using [H-3]-methylyohimbine. After 3 months of treatment, hematocrit increased (p < 0.01), as expected, while mean blood pressure showed non significant changes. Plasma catecholam ine levels increased (p < 0.05), whereas platelet alpha(2)-adrenoceptor den sity decreased (p < 0.01) with respect to the control period No changes in alpha(2)-adrenoceptor affinity (Kd) were observed. We conclude that rHuEPO treatment increases sympathetic activity which in t urn leads to a compensatory down-regulation of alpha(2)-adrenoceptors in he modialysis patients. This decrease of alpha(2)-adrenoceptor density may att enuate the expected blood pressure increase because of the sympathetic acti vation associated with rHuEPO therapy.