Contributions of Nuclear Magnetic Resonance to Renal Biochemistry

Abstract

31P NMR as a descriptive technique is of interest to nephrologists. Particular contributions of 31P NMR to our understanding of renal function may be enumerated.: Free metabolite levels are different from those classically accepted; in particular, ADP and Pi are low with implications for the control of renal metabolism and Pi transport, and, via the phosphorylation potential, for Na+ transport. Renal pH is heterogeneous; between cortex, outer medulla, and papilla, and between cell and lumen, a large pH gradient exists. Also, quantitation between cytosol and mitochondrion of the pH gradient is now feasible. In acute renal failure of either ischemic or nonischemic origin, both ATP depletion and acidification of the renal cell result in damage, with increasing evidence for the importance of the latter. Measurements of renal metabolic rate in vivo suggest the existence of a prodromal phase of acute renal failure, which could lead to its detection at an earlier and possibly reversible stage. Human renal cancers show a unique 31P NMR spectrum and a very acidic environment. Cancer chemotherapy may alter this and detection of such changes with NMR offers a method of therapeutic monitoring with significance beyond nephrology. Renal cortex and medulla have a different T1 relaxation time, possibly due to differences in lipid composition. It seems that NMR spectroscopy has much to offer to the future understanding of the relationship between renal biochemistry and function.