Sodium transport in cultured rat renal papillary collecting tubule

Conference · Sat Mar 01 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5389618

Konieczkowski, M; Dunn, M J

The renal papillary collecting duct (PCD) is the final site for regulation of sodium excretion. Cultured rat RPCT cells were investigated as a model for the PCD. Sodium transport was studied using /sup 22/Na/sup +/ uptake measurements. Steady state Na/sup +/ uptake was measured at 23/sup 0/C in the absence of K/sup +/ and in the presence of 0.1 mM ouabain. /sup 22/Na/sup +/ uptake by the monolayer (157 +/- 9 nmol/lg protein/3 min) was saturable at 100 mM extracellular NaCl and half-maximal uptake occurred at 40 mM NaCl. The sigmoidal velocity curve suggested more than one external binding site for Na/sup +/ as the Hill coefficient was 2. The measured uptake of /sup 22/Na/sup +/ appeared to be intracellular and was regulated by Na/sup +//K/sup +/ ATPase activity, since activation of the Na/sup +//K/sup +/ pump with K/sup +/, reduced /sup 22/Na/sup +/ accumulation seven-fold. The time course for uptake was linear, showed only a single component, and followed first order kinetics with a t/sub 1/2/ of 17 min. Amiloride inhibited /sup 22/Na/sup +/ uptake. A Dixon plot revealed a linear, mixed type of inhibition with a K/sub i/ of 16 ..mu..M amiloride. Over 70% inhibition of total uptake was observed at 0.1 mM amiloride. Lithium was an effective blocker of /sup 22/Na/sup +/ uptake. Chloride replacement uptake by only 20%. These results suggest that sodium uptake by cultured RPCT cells occurs via a saturable, amiloride-inhibitable channel. A Na/sup +/-Cl/sup -/, or a Na/sup +/-K/sup +/-Cl/sup -/ cotransport system does not appear as a major pathway.

• Research Organization: Case Western Reserve Univ., Cleveland, OH
• OSTI ID: 5389618
• Report Number(s): CONF-8604222-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:3
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMALS
ATP-ASE
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MODELS
BIOLOGICAL PATHWAYS
BODY
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CATIONS
CELL CULTURES
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
CLEARANCE
DRUGS
ENZYME ACTIVITY
ENZYMES
EXCRETION
GLYCOSIDES
HALIDES
HALOGEN COMPOUNDS
HYDROLASES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
KINETICS
LIGHT NUCLEI
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
OUABAIN
PHOSPHOHYDROLASES
POTASSIUM COMPOUNDS
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SODIUM 22
SODIUM CHLORIDES
SODIUM COMPOUNDS
SODIUM ISOTOPES
STROPHANTHINS
TRACER TECHNIQUES
TUBULES
VERTEBRATES
YEARS LIVING RADIOISOTOPES