Effect of osmolarity on potassium transport in isolated cerebral microvessels
Potassium transport in microvessels isolated from rat brain by a technique involving density gradient centrifugation was studied in HEPES buffer solutions of varying osmolarity from 200 to 420 mosmols, containing different concentration of sodium chloride, choline chloride, or sodium nitrate. The flux of /sup 86/Rb into and out of the endothelial cells was estimated. Potassium influx was very sensitive to the osmolarity of the medium. Ouabain-insensitive K-component was reduced in hypotonic medium and was increased in medium made hypertonic with sodium chloride or mannitol. Choline chloride replacement caused a large reduction in K influx. Potassium influx was significant decrease when nitrate is substituted for chloride ion in isotonic and hypertonic media, whereas a slight decrease was found in hypotonic medium. The decrease of K influx in the ion-replacement medium is due to a decrement of the ouabain-insensitive component. Potassium efflux was unchanged in hypotonic medium but was somewhat reduced in hypertonic medium. The marked effect of medium osmolarity of K fluxes suggests that these fluxes may be responsible for the volume regulatory K movements. The possible mechanism of changes of K flux under anisotonic media is also discussed.
- Research Organization:
- National Cheng Kung Univ., Tainan (Taiwan)
- OSTI ID:
- 6409430
- Journal Information:
- Life Sci.; (United States), Vol. 43:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
POTASSIUM
MEMBRANE TRANSPORT
BRAIN
CHLORIDES
ENDOTHELIUM
OSMOSIS
OUABAIN
RATS
RUBIDIUM 86
SODIUM COMPOUNDS
TRACER TECHNIQUES
ULTRACENTRIFUGATION
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ALKALI METALS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CENTRAL NERVOUS SYSTEM
CENTRIFUGATION
CHLORINE COMPOUNDS
DAYS LIVING RADIOISOTOPES
DIFFUSION
DRUGS
ELEMENTS
GLYCOSIDES
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
METALS
MINUTES LIVING RADIOISOTOPES
NERVOUS SYSTEM
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
RADIOISOTOPES
RODENTS
RUBIDIUM ISOTOPES
SEPARATION PROCESSES
STROPHANTHINS
TISSUES
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques