title: Temperature- and pH-dependence of proton relaxation rates in rat liver tissue.
abstract: In this study proton NMR relaxation rates R1 and R2 and pH of untreated fresh rat liver tissue as well as changes up to 4 h after tissue excision was investigated. Measurements were performed in the temperature range from 7 to 45 degrees C. Dynamic changes in all parameters were observed at higher temperatures (> or = 30 degrees C). A qualitatively different time course after tissue excision of all three parameters was obtained for 45 degrees C. The relative alterations like the change of relaxation rates referred to a reference value can predict tissue viability. A good correlation between R2 and pH in the range of 7-37 degrees C was detected and is described by an improved analytical model for R2 as a function of temperature and pH. The observed data lead to an empirical model given by R2 (pH,T) = 39.8 + (10.2 * delta pH) + (0.1 * delta T) + (0.2 * delta pH delta T), where the reference pH value was chosen 7.4 and the reference temperature value 37 degrees C (310.15 K), respectively.
authors.affiliation: Arbeitsgruppe NMR, Institut für Medizinische Physik, Universität Wien, Austria.
authors.forename: E
authors.initials: E
authors.lastname: Moser
authors.forename: E
authors.initials: E
authors.lastname: Winklmayr
authors.forename: P
authors.initials: P
authors.lastname: Holzmüller
authors.forename: M
authors.initials: M
authors.lastname: Krssak
mesh_terms: D000818:Animals; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature