title: Estriol improves membrane fluidity of erythrocytes by the nitric oxide-dependent mechanism: an electron paramagnetic resonance study.
abstract: The present in vitro study was performed to investigate the effects of estriol (E3) on membrane fluidity of erythrocytes by means of an electron paramagnetic resonance (EPR) and spin-labeling method. E3 was shown to significantly decrease the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-NS obtained from EPR spectra of erythrocyte membranes. This finding indicated that E3 might increase the membrane fluidity of erythrocytes. The effect of E3 was significantly potentiated by the nitric oxide (NO) donor, S-nitroso-N-acetylpenicillamine (SNAP), and a cyclic guanosine 3',5'-monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change in the membrane fluidity induced by E3 was antagonized by the NO synthase inhibitor, L-NG-nitroarginine-methyl-ester (L-NAME), and asymmetric dimethyl-L-arginine (ADMA). The results of the present study showed that E3 significantly increased the membrane fluidity and improved the microviscosity of erythrocyte membranes, partially mediated by an NO- and cGMP-dependent pathway. Furthermore, the data might be consistent with the hypothesis that E3 could have a beneficial effect on the rheological behavior of erythrocytes and may play a crucial role in the regulation of microcirculation.
authors.affiliation: Department of Medicine, Wakayama Medical University, Japan. tsudak@mail.wakayama-med.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Tsuda
authors.forename: Y
authors.initials: Y
authors.lastname: Shimamoto
authors.forename: K
authors.initials: K
authors.lastname: Kimura
authors.forename: I
authors.initials: I
authors.lastname: Nishio
authors.forename: Y
authors.initials: Y
authors.lastname: Masuyama
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism*; D004964:Estriol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects*; D008875:Middle Aged; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; C018524:N,N-dimethylarginine; D001120:Arginine; D004964:Estriol; D010396:Penicillamine; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester