EFFECT OF CAPTOPRIL ON THE RENAL VENOARTERIAL GRADIENT OF ERYTHROPOIETIN AND OXYGEN IN UNILATERAL RENAL-ARTERY DISEASE

Twenty-nine patients with unilateral renal artery stenosis or occlusion were investigated. The veno-arterial gradient (VA-gradient) of erythropoietin (EPO), haemoglobin oxygen saturation and plasma renin activity (PRA) was determined separately in each kidney before and 1h after angiotensin converting enzyme inhibition (ACE-inhibition). The VA-gradient of EPO and of hemoglobin oxygen saturation were the same in the affected and unaffected kidney during basal conditions. During ACE-inhibition the VA-gradient of EPO disappeared on the affected side but not on the unaffected side. A fall in s-EPO after ACE inhibition was demonstrated in the renal vein on the affected side (-1.4Ul(-1), p<0.01), in the contralateral vein (-0.8Ul(-1), p<0.01) and in the aorta (-0.6U1(-1), p<0.01). The O-2-gradients were reduced on both sides after captopril, from 10.8-7.5% (p<0.04) on the affected side and from 10.8-9.0% p<0.04) on the contralateral. It is suggested that the stimulated reninangiotensin system may be important for EPO production in the affected kidney in unilateral renal disease.