Yajie Zhang1, James A. Balschi1
1Medicine, Brigham and Women's Hospital, Boston, MA, United States
The extracellular relaxation agent, GdDTPA2- was used to distinguish intra- and extracellular 1H2O signals by altering their T1 values. Equilibrium trans-plasma membrane water exchange kinetics were quantified using two-site-exchange analysis to obtain the mean intracellular water life time (i ). Our studies found that i-1 (water exchange) correlated with Na+/K+ ATPase activity in isolated perfused rat hearts. Thus, i-1 acts as a biomarker for the cellular membrane transport activity. Potentially i-1 is altered in pathological states. i can be determined from pharmacokinetic analyses of in vivo 1H2O DCE-MRI studies. These findings could enable high resolution functional metabolic imaging.