1Department
of Chemistry, Washington University in St. Louis, St. Louis, MO, United
States; 2Department of Cell Biology & Physiology, Washington
University in St. Louis, St. Louis, MO, United States; 3Department
of Neurology, Washington University in St. Louis, St. Louis, MO, United
States; 4Department of Pediatrics, Washington University in St.
Louis, St. Louis, MO, United States; 5Department of Radiology,
Washington University in St. Louis, St. Louis, MO, United States
Knowledge of intracellular water preexchange lifetime in neurons and astrocytes is essential for understanding intracellular water diffusion in brain. Employing a previously described cultured cell system, the longitudinal 1H MR relaxation of intracellular water in mixed cultured neurons and astrocytes was distinguished from that of the extracellular media where the apparent relaxation rate was greatly enhanced via either rapid flow or relaxation agent. Under such conditions, where the true intracellular T1 is 50 fold greater than the apparent T1 of the extracellular media (MR slow exchange regime) the intracellular water preexchange lifetime is readily derived, 0.26 &[plusmn] 0.3 s.
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