Does angiotensin II modulate erythropoietin production in HepG2 cells?
GROUND: In humans, infusion of angiotensin II increases erythropoietin (EPO) serum levels in a dose-dependent manner. However, it is not known whether angiotensin II stimulates EPO-producing renal fibroblasts directly via a receptor or by alteration of renal hemodynamics with a consecutive decrease of renal blood flow. The purpose of this study was to investigate EPO secretion and gene expression under direct angiotensin II stimulation in a cell model thereby excluding hemodynamic effects. METHODS: In an established EPO-secreting cell line (HepG2), EPO concentrations were measured under various conditions (normoxia and hypoxia) and different angiotensin II concentrations. mRNA levels of EPO were analyzed by LightCycler quantitative PCR after reverse transcription normalized to the housekeeping gene cyclophilin. RESULTS: Angiotensin II did not affect EPO production in any concentration (1 nM or 100 microM) under conditions of normoxia. Reduced oxygen tension (1% O2) led to the expected
