Highresolution 1Hn.m.r. studies ofvertebrate blood andplasma

SpinechoFourier transform proton n.m.r. spectra ofwholeblood contain resonances frombotherythrocytes andplasma. A large numberofwell-resolved signals from mobile protons oflow-molecular-weight metabolites inplasma andserumhavebeen identified. Spectra fromtheplasmas ofeight animal species andcommercial, quality control sera arecompared. CaEDTA2- andMgEDTA2-resonances canbeusedforthe simultaneous determination ofEDTA-chelatable calcium andmagnesium concentrations inintact plasma andother biological fluids. Cholesterol istooimmobile to contribute tothespectra ofintact plasma, butisreadily estimated byn.m.r. inbothits free andesterified forms after extraction into methanol. Ourinterest inthemetabolism ofmetal compounds ledustoinvestigate theapplication of'H n.m.r. methods toastudy ofintact humanblood. Suchstudies arehampered bythelarge number of overlapping resonances andbythelarge signal from water. Previous workers haveshownthatbothof these canbelargely overcome byusing theSEFT (Brown etal., 1977;Rabenstein & Nakashima, 1979) ormagnetization transfer (Rabenstein etal., 1980) techniques combined withhighfrequency observation (e.g. 400MHz).IntheSEFTtechnique broadresonances frommacromolecules and otherrelatively immobile groupsdisappear via spin-spin (T2) relaxation during thewaiting periods (r)ofthetwopulse sequence. Inmagnetization transfer, selected protein resonances areirradiated andtheremainder oftheprotein envelope is effectively saturated viaspin diffusion during asmall time delay before theobservation pulse isapplied. 'Hn.m.r. spectra fromblood appeared toconsist ofresonances fromredcells observed previously (Brown etal., 1977; Brindle etal., 1979; Brown& Campbell, 1980) together withresonances from plasma. However, spectra fromplasma alone were morehighly resolved andreproducible. Inthis paper wediscuss theassignment ofresonances including freeaminoacids, creatine, glucose, lactate, D3-hydroxybutyrate,