17β-Estradiol attenuates vascular contraction through inhibition of RhoA/Rho kinase pathway

We hypothesized that 17β-estradiol attenuates vascular contraction through inhibition of RhoA/Rho kinase pathway. Rat aortic rings were contracted with cumulative addition of U46619, NaF, KCl or PDBu 30 min after pretreatment with 17β-estradiol (10, 30, and 100 μM) or vehicle. We measured the amount of GTP RhoA and the level of phosphorylation of the myosin light chain (MLC₂₀), myosin phosphatase targeting subunit 1 (MYPT1) and PKC-potentiated inhibitory protein for heterotrimeric MLCP of 17 kDa (CPI17). Pretreatment with 17β-estradiol dose-dependently inhibited the concentration-response curves in response to U46619, NaF or KCl, but not to PDBu. 17β-Estradiol decreased not only the level of phosphorylation of MYPT1^Thr855 and CPI17^Thr38 as well as MLC₂₀, but also the activity of RhoA induced by U46619 or NaF. However, 17β-estradiol did not affect the level of phosphorylation of CPI17 induced by PDBu. 17β-Estradiol attenuates vascular contraction through inhibition of RhoA/Rho kinase pathway.