Novel application of complimentary imaging techniques to examine in vivo glucose metabolism in the kidney

The metabolic status of the kidney is a determinant of injury susceptibility and a measure of progression for many disease processes, however, noninvasive modalities to assess kidney metabolism are lacking. In this study we employed positron emission tomography (PET) and intravital multiphoton microscopy (MPM) to assess cortical and proximal tubule glucose tracer uptake respectively following experimental perturbations of kidney metabolism. Applying dynamic image acquisition PET with 2-18fluoro-2-deoxyglucose (18F-FDG) and tracer kinetic modeling we found that an intracellular compartment in the cortex of the kidney could be distinguished from the blood and urine compartments in animals. Given emerging literature that the tumor suppressor protein p53 is an important regulator of cellular metabolism, we demonstrated that PET imaging was able to discern a three-fold increase in cortical 18F-FDG uptake following the pharmacologic inhibition of p53 in animals. Intravital MPM with the fluorescent glucose analogue 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) provided increased resolution and corroborated these findings at the level of the proximal tubule. Extending our observation of p53 inhibition on proximal tubule glucose tracer uptake, we demonstrated by intravital MPM that pharmacologic inhibition of p53 diminishes mitochondrial potential difference. We provide additional evidence that inhibition of p53 alters key metabolic enzymes regulating glycolysis and increases intermediates of glycolysis. In summary we provide evidence that PET is a valuable tool to examine kidney metabolism in preclinical and clinical studies, intravital MPM is a powerful adjunct to PET in preclinical studies of metabolism, and p53 inhibition alters basal kidney metabolism.