title: Determination of intracellular pH and compartmentation using diffusion-weighted NMR spectroscopy with pH-sensitive indicators.
abstract: The intracellular pH (pHi) of a series of cancer cell lines was determined using the pH-sensitive indicators imidazole (Im) or histidine (His) and diffusion-weighted (DW) proton NMR spectroscopy. The DW method allows the observation at high magnetic field gradient values of only the slow-moving (intracellular) components, thus ensuring complete separation between intra- and extracellular components. Using the chemical shift difference (deltadelta) between the imidazole ring C2-H and C4(5)-H peaks, we were able to measure the pHi independently of chemical shift standardization. With His, the cell lines gave pHi values of approximately 6.5-7.0, whereas with Im, a second, more acidic compartment (pHi = 5.5-5.8) was also observed. An inverse correlation was also found between pHi and the intracellular lactate concentration. This method may be applicable to in vivo pH determinations.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Hebrew University, Jerusalem, Israel.
authors.forename: Jack S
authors.initials: JS
authors.lastname: Cohen
authors.forename: Menachem
authors.initials: M
authors.lastname: Motiei
authors.forename: Shani
authors.initials: S
authors.lastname: Carmi
authors.forename: Dana
authors.initials: D
authors.lastname: Shiperto
authors.forename: Odeya
authors.initials: O
authors.lastname: Yefet
authors.forename: Israel
authors.initials: I
authors.lastname: Ringel
mesh_terms: D002138:Calibration; D002451:Cell Compartmentation; D045744:Cell Line, Tumor; D006639:Histidine / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D007093:Imidazoles; D006639:Histidine; C029899:imidazole