Yajie Zhang1, Marie Poirier-Quinot2, Charles S. Springer3, James A. Balschi1
1NMR Laboratory for Physiological Chemistry, Brigham and Women's Hospital, Boston, MA, USA; 2Unite de Recherche en Resonance Magnetique Medicale, University of Paris Sud, Orsay, France; 3Advanced Imaging Research Center, Oregon Health Science University, Portland, OR, USA
The extracellular relaxation agent, GdDTPA2- was used to distinguish intra- and extracellular 1H2O signals by altering their T1 values. Equilibrium transcytolemmal water exchange kinetics were quantified using two-site-exchange analysis to obtain the mean intracellular water life time (i). The hypothesis that i correlates with cellular energetics was tested in yeast cells. i was inversely linearly correlated with cellular ATP content. Thus, i acts as a sensitive biomarker for the cellular energetics. i can be determined from pharmacokinetic analyses of in vivo 1H2O DCE-MRI studies. This could allow much higher resolution cellular energetics mapping than with in vivo 31P MRI.