31P-NMR studies on time-course of change in the blood-brain barrier after treatment with hypertonic solution.

The time-course of change in permeability of the blood-brain barrier to ions after treatment with hypertonic solution was examined by studies on the intracellular pH of the brain by 31P-NMR spectroscopy. Results showed that during infusion of NaHCO3, the intracellular pH of the brain increased within 2.5 min after infusion of hypertonic mannitol and returned to the initial value within 25 min. A similar change in the intracellular pH of the brain was induced after a second infusion of hypertonic mannitol solution, indicating that this change was reversible.