Dynamics of NAD in cortical nephron segments: Effect of nicotinamide and of dietary phosphate intake

Journal Article · Sat Aug 01 00:00:00 EDT 1987 · American Journal of Physiology; (USA)

OSTI ID:5030358

Yusufi, A N.K.; Kiebzak, G M; Kusano, E; Werness, J L; Homma, S; Dousa, T P ^[1]

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1. Mayo Clinic and Foundation, Rochester, MN (USA)

NAD content and the rate of NAD hydrolysis were determined in proximal convoluted tubules (PCT), proximal straight tubules (PST), and adjacent cortical nephron segments microdissected from kidneys of tyroparathyroidectomized (TPTX) rats. In the basal state, rats fed a normal phosphate diet had an NAD content higher in PCT, PST, and in cortical ascending limb (CAL) than in glomeruli. After intraperitoneal injection of nicotinamide, the NAD content increased significantly in all nephron segments except CAL. In experiments conducted on TPTX rats stabilized on a low-phosphorus diet, NAD content increased in response to a nicotinamide injection in PCT, but did not change significantly in PST. The catabolism of NAD was determined by generation of ({sup 3}H)adenosine, a major metabolite of (adenine-2,8-{sup 3}H)NAD. The rate of ({sup 3}H)adenosine generation from ({sup 3}H)NAD was significantly higher in PST than in PCT. The authors conclude that, in response to nicotinamide administration in vivo, the NAD content increases more in PCT than in PST and that this difference may be, at least partly, due to a lower rate of NAD breakdown in PCT. In a state of dietary phosphate deprivation, NAD also increases significantly in response to intraperitoneal nicotinamide in PCT, but it does not increase significantly in PST. The nicotinamide-elicited increase of NAD content in proximal tubules, mainly in PCT, may be related to inhibition of Na{sup +}-gradient-dependent inorganic phosphate (P{sub i}) reabsorption across the brush-border membrane proximal tubules and to the phosphaturic effect of nicotinamide in rats red normal-P{sub i} diet.

• OSTI ID: 5030358
• Journal Information: American Journal of Physiology; (USA), Vol. 253:2; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
KIDNEYS
PHYSIOLOGY
NAD
CATABOLISM
NICOTINAMIDE
BIOLOGICAL EFFECTS
ABSORPTION
ADENOSINE
CELL MEMBRANES
DIET
PHOSPHATES
RATS
TRITIUM COMPOUNDS
AMIDES
ANIMALS
AZINES
BODY
CELL CONSTITUENTS
COENZYMES
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
MAMMALS
MEMBRANES
METABOLISM
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PYRIDINES
RIBOSIDES
RODENTS
VERTEBRATES
VITAMIN B GROUP
VITAMINS
550201* - Biochemistry- Tracer Techniques