title: On the oxygenation-dependent (129)Xe T (1) in blood.
abstract: The spin-lattice relaxation time, T(1), of hyperpolarized (129)Xe in blood is sensitive to blood oxygenation. In particular, it has been shown that (129)Xe T(1) is shorter in venous blood than in arterial blood. We have studied the T(1) of hyperpolarized (129)Xe dissolved in human blood as a function of blood oxygenation level, sO(2), in the physiological oxygenation range. We show that the (129)Xe relaxation rate, T(1)(-1), varies in a nonlinear fashion as a function of sO(2). This finding suggests that direct interaction of xenon with the paramagnetic heme group of deoxyhemoglobin is not the dominant oxygenation-dependent relaxation mechanism for (129)Xe in blood. These results corroborate the idea that the oxygenation-dependence of (129)Xe T(1) is determined by conformational changes of hemoglobin induced by oxygen binding.
authors.affiliation: CRC Clinical Magnetic Resonance Research Group, The Institute of Cancer Research, The Royal Marsden NHS Trust, Sutton, Surrey SM2 5PT, UK.
authors.forename: J
authors.initials: J
authors.lastname: Wolber
authors.forename: A
authors.initials: A
authors.lastname: Cherubini
authors.forename: M O
authors.initials: MO
authors.lastname: Leach
authors.forename: A
authors.initials: A
authors.lastname: Bifone
mesh_terms: D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019906:Nuclear Magnetic Resonance, Biomolecular; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000737:chemistry / Q000378:metabolism; D010313:Partial Pressure; D011487:Protein Conformation; D014978:Xenon / Q000097:blood*; D014979:Xenon Isotopes
chemical_list: D010108:Oxyhemoglobins; D014979:Xenon Isotopes; D002245:Carbon Dioxide; D014978:Xenon; D010100:Oxygen