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Title: 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.
Authors:
Publication Date:
OSTI Identifier:
6409430
Resource Type:
Journal Article
Resource Relation:
Journal Name: Life Sci.; (United States); Journal Volume: 43:4
Research Org:
National Cheng Kung Univ., Tainan (Taiwan)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 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