Phosphorus-31 nuclear magnetic resonance study of healthy human saliva

Phosphorus nuclear magnetic resonance spectra of whole, mandibular and parotid salivas from healthy humans all presented single broad inhomogeneous lines, the widths arising from the chemical-shift distribution of the resonances of the constituent inorganic phosphate compounds. Spin–lattice relaxation of phosphorus in the stimulated parotid saliva was characterized by a single time constant of T1, whereas the spin–spin relaxation was found to be determined by the chemical exchange rates. The results indicate that calcium phosphates found in parotid saliva are involved in at least two chemical exchange processes. The dissociation rates for the fast and slow exchange were estimated to be 1.5/sec and 0.2/sec, respectively.