title: Influence of sodium nitroprusside on human erythrocyte membrane water permeability: an NMR study.
abstract: Sodium nitroprusside (SNP) is a nitric oxide (•NO) donor in vitro and in vivo. In this paper the time variation of the intracellular water proton nuclear magnetic resonance (NMR) effective relaxation time T'(2a) in SNP-treated human erythrocyte suspensions, containing 10 mM membrane impermeable paramagnetic MnCl2, has been measured. The observed T'(2a) time-course was analyzed in terms of the two mechanisms by which released •NO affects T'(2a). These are, respectively, enhancement of the intracellular water proton intrinsic NMR relaxation rate 1/T(2a) by paramagnetism of •NO subsequently bonded to iron atoms of intracellular deoxyhemoglobin, and suppression of diffusional water permeability P(d) as a consequence of nitrosylation of aquaporin-1 (AQP1) channel Cys189, either by direct reaction with •NO or with one of the •NO oxidation products, such as N2O3. The bound •NO on the Cys189 thiol residue appears to impose a less efficient barrier to water permeation through AQP1 than the larger carboxyphenylmercuryl residue from p-chloromercuribenzoate. The effect of •NO on P(d) is discussed in terms of NO-induced vasodilation.
authors.affiliation: J. Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. gojmir.lahajnar@ fmf.uni-lj.si
authors.forename: Gojmir
authors.initials: G
authors.lastname: Lahajnar
authors.forename: Barbara
authors.initials: B
authors.lastname: Sobotič
authors.forename: Ana
authors.initials: A
authors.lastname: Sepe
authors.forename: Vojko
authors.initials: V
authors.lastname: Jazbinšek
authors.forename: Slavko
authors.initials: S
authors.lastname: Pečar
mesh_terms: D002463:Cell Membrane Permeability / Q000187:drug effects*; D004058:Diffusion; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D014867:Water / Q000378:metabolism*
chemical_list: D020030:Nitric Oxide Donors; D014867:Water; D009599:Nitroprusside