General Physiology and Biophysics Vol.29, No.4, p.373-380, 2010
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Title: Influence of sodium nitroprusside on human erythrocyte membrane water permeability: an NMR study |
Author: Gojmir Lahajnar, Barbara Sobotič, Ana Sepe, Vojko Jazbinšek and Slavko Peča |
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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/T2a by paramagnetism of •NO subsequently bonded to iron atoms of intracellular deoxyhemoglobin, and suppression of diffusional water permeability Pd 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 Pd is discussed in terms of NO-induced vasodilation.
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Keywords: Human erythrocytes — Water permeability coefficient — Sodium nitroprusside — Proton NMR transverse relaxation time |
Year: 2010, Volume: 29, Issue: 4 |
Page From: 373, Page To: 380 |
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doi:10.4149/gpb_2010_04_373
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