The experimental program will be directed toward an elucidation of the factors which regulate ammonia synthesis by the mammalian kidney. The proposed studies will be formed utilizing isolated renal cortical mitochondria to obtain kinetic data defining the characteristics of glutamine transport across the mitochondrial membrane. The role of the transport and metabolism of glutamate and Alpha-ketoglutarate on glutamine transport and deamidation will be evaluated. Further studies will be carried out to relate the accelerated rate of glutamate dehydrogenase flux occurring in acidosis to the mitochondrial oxidation reduction potential, protein synthesis and augmented Alpha-ketoglutarate oxidation. The control of Alpha-ketoglutarate dehydrogenase flux will be investigated in detail by assessment of the role of calcium and H+ on the enzyme in kidney and liver. As part of this evaluation, mictochondrial free calcium and mitochondrial calcium efflux will be measured as a function of external pH. Utilizing cell fractionation methods, analysis of metabolite and pH profiles in the cytosolic and mitochondrial compartments of isolated renal tubules will be performed to provide further insight into alterations in renal metabolism in acidosis. The role of adrenal steroids in renal glutamine and glutamate metabolism will also be investigated, utilizing isolated mitochondria and renal tubules. Experiments will also be performed in kidney mitochondria from uremic rats. These studies will provide further insight into the biochemical mechanisms underlying the control of renal ammoniagenesis.