Nitric oxide is a determinant of membrane fluidity of erythrocytes in postmenopausal women: an electron paramagnetic resonance investigation

• Published in: American journal of hypertension Vol. 16; no. 3; pp. 244 - 248
• Main Authors: Tsuda, Kazushi, Kinoshita-Shimamoto, Yukiko, Kimura, Keizo, Nishio, Ichiro
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.03.2003; Oxford University Press; Elsevier Science
• Subjects: Aged; Biological and medical sciences; Blood Pressure; electron paramagnetic resonance; Electron Spin Resonance Spectroscopy; Erythrocyte Membrane - metabolism; erythrocytes; Female; Hematology; Humans; hypertension; Hypertension - metabolism; Hypertension - physiopathology; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; membrane fluidity; Membrane Fluidity - physiology; Microcirculation; Middle Aged; Nitrates - blood; nitric oxide; Nitric Oxide - metabolism; Nitrites - blood; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Postmenopausal women; Postmenopause; nitric oxide; Postmenopausal women; erythrocytes; electron paramagnetic resonance; hypertension; membrane fluidity; Human; Hypertension; Red blood cell; Cardiovascular disease; Exploration; Spin labelling; Regulation(control); Fluidity; Nitric oxide; Plasma membrane; Postmenopause; Electron paramagnetic resonance; Comparative study
• ISSN: 0895-7061; 1879-1905; 1941-7225
• DOI: 10.1016/S0895-7061(02)03261-2

In the present study, to determine a possible role of nitric oxide (NO) in the regulation of membrane functions, we examined the relationship between plasma NO level and membrane fluidity of erythrocytes in postmenopausal women. We evaluated the membrane fluidity of erythrocytes obtained from hypertensive and normotensive postmenopausal women by means of an electron paramagnetic resonance (EPR) and spin labeling method. The EPR study revealed that the order parameter (S) for 5-nitroxide stearate in erythrocyte membranes was significantly greater in hypertensive postmenopausal women than in normotensive postmenopausal women. The finding indicated that the membrane fluidity of erythrocytes was decreased in hypertensive postmenopausal women compared with normotensive postmenopausal women. The plasma level of the NO metabolites (nitrite and nitrate) while fasting was significantly lower in hypertensive postmenopausal women than in normotensive postmenopausal women. In addition, the order parameter (S) in the EPR spectra of erythrocyte membranes was inversely correlated with the plasma NO metabolite level, which indicated that the lower membrane fluidity of erythrocytes was associated with the lower plasma NO level in postmenopausal women. These results are consistent with the hypothesis that NO may have a crucial role in the regulation of membrane fluidity of erythrocytes in postmenopausal women.