Transcriptional regulation in eukaryotes: Carey, M., Smale, S. T.

Abstract

AIM: To study the effect of E6, a novel calmodulin inhibitor, on the activity of P-glycorprotein (P-gp) in purified primary cultured rat brain microvessel endothelial cells (RBMEC). METHODS: Flow cytometry was used to purify RBMEC from other cell types. Fluorescence of P-gp substrate rhodamine 123 (Rh123) in RBMEC was measured to evaluate the effect of E6 on the function of P-gp. RESULTS: Purified RBMEC was obtained after being sorted from other cell types by flow cytometry. Intracellular fluorescence of Rh123 in RBMEC increased after incubation with E6 3, 10 mumol/L or verapamil (VER) 50 mumol/L (P<0.01), respectively. After the treatment of E6 10 mumol/L, intracellular Rh123 accumulation was increased nearly to 3-fold. E6 and VER have no effect on accumulation of Rh123 in human umbilical vein endothelial cells (HUVEC), which do not express P-gp. CONCLUSION: E6 exhibited a strong inhibitory effect on the activity of P-gp in RBMEC.