QUANTITATION OF INTRACELLULAR [NA-VIVO BY USING TMDOTP5- AS AN NMR SHIFT-REAGENT AND EXTRACELLULAR MARKER(] IN)

A method is presented to measure the absolute concentration of intrace llular Na+ ([Na+](i)) in vivo by using interleaved Na-23- and P-31-nuc lear magnetic resonance (NMR) spectroscopy and TmDOTP5- as shift reage nt and chemical marker of tissue extracellular space (ECS). The techni que was used to determine [Na+](i) and relative ECS in Livers of contr ol rats (21 +/- 3 and 0.11 +/- 0.02 mM, respectively) and in rats expo sed to carbon tetrachloride (103 +/- 29 and 0.23 +/- 0.03 mM, respecti vely). The NMR measurements were confirmed independently on excised ti ssue samples by using atomic absorption spectroscopy. The results conf irm that TmDOTP5- can be used as a combined cation shift reagent; and ECS marker, thereby allowing quantitation of [Na+](i) in vivo by NMR.