Unidirectional potassium fluxes in renal distal tubule: effects of chloride and barium

Journal Article · Thu May 01 04:00:00 EDT 1986 · Am. J. Physiol.; (United States)

OSTI ID:5528602

Ellison, D H; Velazquez, H; Wright, F S

Low luminal concentrations of chloride stimulate net potassium secretion by the renal distal tubule, independent of changes in transepithelial voltage. These effects are not prevented by the luminal application of the potassium channel blocking agent barium. Because net potassium secretion comprises secretory and absorptive components, we sought to evaluate the effects of chloride and barium on unidirectional potassium fluxes in the renal distal tubule. In vivo microperfusion methods were used in anesthetized Sprague-Dawley rats. Perfusion solutions contained either /sup 42/K or /sup 86/Rb as tracers for potassium. Tracer efflux coefficients, indicating apparent potassium permeability, were similar when measured using either isotope. Net potassium flux was determined as the difference between perfusion and collected rate, and unidirectional absorptive potassium flux was calculated as the product of the mean luminal potassium concentration and the tracer efflux coefficient. During perfusion with a solution that resembled fluid normally arriving at the early distal tubule, the absorptive potassium flux was approximately 25% of the unidirectional secretory flux. Reducing lumen chloride concentration increased net potassium secretion, because blood-to-lumen potassium flux increased from 61 +/- 12.7 to 96 +/- 14.6 pmol/min. Barium reduced both absorptive and secretory fluxes but did not prevent the stimulation of net potassium secretion that occurs when luminal chloride concentration is reduced. Apparent potassium permeability during perfusion with a solution that resembled fluid normally arriving at the early distal tubule was 800 nm/s when corrected for voltage.

• Research Organization: Yale Univ. School of Medicine, New Haven, CT
• OSTI ID: 5528602
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States); ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALI METALS
ALKALINE EARTH METALS
ANIMALS
BARIUM
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOELECTRICITY
BIOLOGICAL EFFECTS
BODY
CHLORIDES
CHLORINE COMPOUNDS
DAYS LIVING RADIOISOTOPES
ELECTRICITY
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
MAMMALS
MEMBRANE TRANSPORT
METALS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANS
PERFUSED ORGANS
PERMEABILITY
POTASSIUM
RADIOISOTOPES
RATS
RODENTS
RUBIDIUM 86
RUBIDIUM ISOTOPES
SECRETION
SODIUM
TRACER TECHNIQUES
TUBULES
VERTEBRATES