Renin-angiotensin system stimulates erythropoietin secretion in chronic hemodialysis patients
Vlahakos, D.V.; Balodimos, C.; Papachristopoulos, V.; Vassilakos, P.; Hinari, E.; Vlachojannis, J.G.
Clinical Nephrology 43(1): 53-59
1995
ISSN/ISBN: 0301-0430 PMID: 7697936 Document Number: 443571
A series of observations suggests an interrelationship between the renin-angiotensin system (RAS) and erythropoietin (EPO) secretion. To further evaluate the role of RAS in erythropoiesis of chronic hemodialysis patients, we studied two groups of such patients: Group A consisted of 16 patients (14 male and 2 female, 54.7 +- 3.3 years old), who maintained a target hematocrit value of 0.30 (0.32 +- 0.01), without recombinant human EPO (rhEPO) supplementation. Group B consisted of 14 patients (7 male and 7 female, 50 +- 5.3 years old), who required subcutaneous injections of rhEPO (90.8 +- 10 IU cntdot kg-1 cntdot week-1), to maintain the same target hematocrit value of 0.30 (30 +- 0.01). Plasma renin activity (PRA) was found to be the major feature to distinguish patients in these two Groups and it was five times higher in Group A (10 +- 2 ng cntdot ml-1 cntdot h-1) compared to Group B patients (1.8 +- 0.6 ng cntdot m-l-1 cntdot h-1) (p lt 0.001). Moreover, activation of RAS in Group A patients by volume depletion (2.2 +- 0.21) during hemodialysis resulted in a 118 +- 33 percent increment of PRA (p lt 0.01) which was accompanied by a 69 +- 25 percent increment of serum EPO levels (p lt 0.05). Repetition of the same protocol after inhibiting the converting enzyme with 50 mg of Captopril prior to dialysis session, resulted in a 315 +- 64 percent increment of PRA (p lt 0.001), while at the same time completely blocked the expected rise in serum EPO levels (1.25 +- 12.5 percent increment). These findings provide persuasive evidence strongly linking EPO secretion to RAS activation in chronic hemodialysis patients.