Changes of beta-Endorphin in Patients with Maintenance Hemodialysis

Lee, Eun Young; Choi, Kyu Bok; Yoon, Kyun Il

Abstract

OBJECTIVE
beta-endorphin, most potent endogenous opioid peptide, is known to play an important role in many homeostatic systems such as the maintenance of blood pressure, regulation of body temperature and the control of pituitary hormone secretion. Previous reports of plasma levels of beta-endorphin in patients with chronic renal failure have mostly shown elevated levels. But the effect of hemodialysis on the plasma levels of beta-endorphin in patients with maintenance hemodialysis is controversial. The aim of this study was to evaluate the effect of a hemodialysis session on the plasma concentrations of beta-endorphin in patients with end-stage renal disease and also to investigate changes of hemodynamic response according to the changes of plasma levels of beta-endorphin.
METHODS
The study group comprised 36 patients who had received regular hemodialysis. Blood for analysis of beta -endorphin was sampled before and immediately after hemodialysis and measured by immunoradiometric assay. Extracellular fluid / total body water (ECF/TBW) was measured before and after the hemodialysis session by multifrequency bioimpedance analyzer (InBody 2.0 , Biospace Co., Ltd., Seoul, Korea). Systolic and diastolic blood pressure were measured by Centrysystem 3 BP monitor every 30 minutes.
RESULTS
1) As a whole, the predialysis beta-endorphin did not differ significantly from postdialysis levels. Blood pressure increased significantly during dialysis. The postdialysis value of ECF/TBW was significantly decreased(0.37+/-0.02 vs. 0.34+/-0.02, p<0.01). 2) The patients were divided into 2 groups according to the pre-, and post-dialysis beta-endorphin levels(Group 1, predialysis beta-endorphin > postdialysis beta-endorphin(n=23) ; group 2, predialysis beta-endorphin < or = postdialysis beta -endorphin(n=13)). 3) During dialysis, the systolic and diastolic blood pressure increased significantly in group 1(p<0.05), but not in group 2. 4) The postdialysis value of ECF/TBW was significantly decreased from baseline value to reference range (0.34+/-0.01) in group 1, but to above the reference range in group 2. 5) The plasma concentrations of beta-endorphin did not change by administration of recombinant human erythropoietin.
CONCLUSION
In conclusion, the elevation in plasma beta-endorphin concentrations probably occur to balance the changes in vasoconstrictive substances. An increase in vasoconstrictive substances is mainly secondary to the decrease in plasma volume during hemodialysis. The data also suggest that certain vasoactive substances might participate in the hemodynamic response to hemodialysis although their exact roles remain to be further elucidated.