This project proposes to investigate in vitro the sources of urinary ammonia nitrogen. Of particular interest is the possibility that amino acids other than glutamine are important nitrogen donors to renal ammonia, depending upon acid-base status. The influence of pH on ammonia formation from either the amide or alpha nitrogens of glutamine is also a target of study. Emphasis is placed on the respective roles of the purine nucleotide cycle and the glutamate dehydrogenase reactions as metabolic pathways of renal ammoniagenesis. The relationship between ammoniagenesis and the metabolism of alpha-ketoglutarate, particularly the role this organic acid plays in stimulating ammonia formation from glutamate, is another investigative focus. Experiments will be performed in rat kidney cortex slices, isolated renal tubules, kidney mitochondria, and the isolated perfused kidney. A unique feature of the project is the utilization of 15N as a tracer for renal nitrogen metabolism and the utilization of gas chromatography-mass spectrometry to quantitate 15N levels in this tissue. The data so generated will be of scientific value in improving our understanding of renal nitrogen metabolism.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK034771-03
Application #
3233008
Study Section
General Medicine B Study Section (GMB)
Project Start
1984-12-01
Project End
1987-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Children's Hospital of Philadelphia
Department
Type
DUNS #
073757627
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Sahai, A; Nissim, I; Tannen, R L (1991) Pathways of acute pH regulation of ammoniagenesis in LLC-PK1 cells: study with [15N]glutamine. Am J Physiol 261:F481-7
Nissim, I; States, B; Nissim, I et al. (1991) The role of gamma-glutamyl transpeptidase in glutamine metabolism by cultured human kidney cells. Contrib Nephrol 92:191-9
Nissim, I; Nissim, I; Yudkoff, M (1991) Adaptation of renal tricarboxylic acid cycle metabolism to various acid-base states: study with [3-13C,5-15N]glutamine. Miner Electrolyte Metab 17:21-31
Nissim, I; Wehrli, S; States, B et al. (1991) Analysis and physiological implications of renal 2-oxoglutaramate metabolism. Biochem J 277 ( Pt 1):33-8
Weinberg, J M; Nissim, I; Roeser, N F et al. (1991) Relationships between intracellular amino acid levels and protection against injury to isolated proximal tubules. Am J Physiol 260:F410-9
Nissim, I; Nissim, I; Yudkoff, M (1990) Carbon flux through tricarboxylic acid cycle in rat renal tubules. Biochim Biophys Acta 1033:194-200
Nissim, I; Korzets, Z (1990) Ammonia metabolism in cultured renal cells. Miner Electrolyte Metab 16:270-6
Nissim, I; Yudkoff, M; Nissim, I et al. (1989) Effect of 5-amino-4-imidazolecarboxamide riboside (AICA-riboside) on the purine nucleotide synthesis and growth of rat kidney cells in culture: study with [15N]aspartate. J Cell Physiol 138:536-40
Nissim, I; States, B (1989) Ammoniagenesis by cultured human renal cortical epithelial cells: study with 15N. Am J Physiol 256:F187-96
Nissim, I; Yudkoff, M; Segal, S (1988) Interrelationships between renal TCA-cycle metabolism and ammoniagenesis: studies with 13C-NMR and GC-MS. Contrib Nephrol 63:60-70