High-resolution magic angle spinning H-1 NMR spectroscopic studies on intact rat renal cortex and medulla

High-resolution magic angle spinning H-1 NMR (MAS-NMR) spectroscopy was use d to investigate the biochemical composition of normal renal cortex and ren al papilla samples from rats, and results were compared with those from con ventional H-1 NMR analysis of protein-free tissue extracts. H-1 MAS NMR spe ctra of samples obtained from inner and outer cortex were found to be broad ly similar in terms of metabolite profile, and intra- and inter-animal vari ability was small. However, the MAS NMR spectra from renal papilla samples were qualitatively and quantitatively different from those obtained from co rtex. High levels of free amino acids and several organic acids were detect ed in the cortex, together with choline, glucose, and trimethylamine-N-oxid e, The dominant metabolite resonances observed in papillary tissue were fro m glycerophosphocholine (GPC), betaine, myo-inositol, and sorbitol, On incr easing the magic angle spinning rate from 4,200 to 12,000 Hz, the lipid MAS H-1 NMR signal profile remained largely unchanged in papillary tissue, whe reas "new" resonances from triglycerides appeared in the spectra of cortica l tissue, this effect being reversible on returning the spinning rate to 4, 200 Hz, Further investigation into the behavior of the lipid components und er different spinning rates suggested that the lipids in the cortex were pr esent in more motionally constrained environments than those in the papilla , H-1 MAS NMR spectra of tissues are of value both in interrogation of the biochemical composition of whole tissue, and in obtaining information on th e mobility and compartmentalization of certain metabolites. (C) 1999 Wiley- Liss, Inc.