Potassium transport in apical membrane vesicles from rabbit kidney cortex
K/sup 42/ or Rb/sup 86/ uptake was studied under equilibrium conditions in apical membrane vesicles prepared by Mg aggregation, differential centrifugation techniques from rabbit kidney cortex. The presence of apical vesicles was verified by 12-fold enrichment of alkaline phosphatase activity and the absence of basolateral vesicles by absence of ouabain-inhibitable Na-K, ATPase activity. Solutions contained 10 mM KCl, 40 mM TMA-Cl, 180 mM mannitol and 1 mM amiloride and were buffered to pH 7.5. Vesicular tracer uptake was linear from 0.25 to 2 min. The slope of that regression line was used to determine the initial exchange rate.K/sup 42/ and Rb/sup 86/ exchange rates did not differ. Increasing the temperature from 21 to 37/sup 0/C raised the exchange rate from 4.16 +/- .44 to 6.93 +/- 40 nEq/min/mg protein (n=5, p < .001). Q/sub 10/ = 1.70. Reducing pH from 7.5 to 6.0 reduced exchange from 7.48 +/- 1.21 to 4.28 +/- .51 nEq/min/mg prot. (n=5, p < .05). The dependence of 1 min tracer exchange on K concentration was investigated. The change in exchange rate was linear over the range of 1 to 20 mM with no evidence of saturation. The channel blocker TEA-Cl (10 mM in and out) did not affect exchange (p > .4). 1 mM external BaCl/sub 2/ reduced exchange from 5.50 +/- .78 to 3.82 +/- .71 nEq/min/mg prot. (n=5, p > .05). These results suggest that in the presence of amiloride, K exchange occurs via channels that are sensitive to temperature, pH and barium.
- Research Organization:
- Univ. of Kansas Medical Center, Kansas City
- OSTI ID:
- 5418015
- Report Number(s):
- CONF-8604222-; TRN: 86-030412
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
POTASSIUM
MEMBRANE TRANSPORT
ALKALINE PHOSPHATASE
CELL MEMBRANES
ENZYME ACTIVITY
KIDNEYS
PH VALUE
POTASSIUM 42
RABBITS
RUBIDIUM 86
TEMPERATURE DEPENDENCE
TRACER TECHNIQUES
ALKALI METAL ISOTOPES
ALKALI METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENZYMES
ESTERASES
HOURS LIVING RADIOISOTOPES
HYDROLASES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANES
METALS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANS
PHOSPHATASES
POTASSIUM ISOTOPES
RADIOISOTOPES
RUBIDIUM ISOTOPES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques