Effects of internal and external pH on amiloride-blockable Na transport across toad urinary bladder vesicles
The authors have examined the effect of internal and external pH on Na+ transport across toad bladder membrane vesicles. Of the total SSNa uptake measured 0.5-2.0 min after introducing tracer, 80 +/- 4% (mean +/- SE, n = 9) is blocked by the diuretic with a KI of 2 X 10(-8) M. Thus, this amiloride-sensitive flux is mediated by the apical sodium-selective channels. Varying the internal (cytosolic) pH over the physiologic range 7.0-8.0 had no effect on sodium transport; this result suggests that variation of intracellular pH in vivo has no direct apical effect on modulating sodium uptake. On the other hand, SSNa was directly and monotonically dependent on external pH. External acidification also reduced the amiloride-sensitive efflux across the walls of the vesicles. This inhibition of 22Na efflux was noted at external Na concentrations of both 0.2 microM and 53 mM. These results are different from those reported with whole toad bladder. A number of possible bases for these differences are considered and discussed. They suggest that the natriferic response induced by mucosal acidification of whole toad urinary bladder appears to operate indirectly through one or more factors, presumably cytosolic, present in whole cells and absent from the vesicles.
- Research Organization:
- Weizmann Inst. of Science, Rehovot (Israel)
- OSTI ID:
- 6255901
- Journal Information:
- J. Membr. Biol.; (United States), Vol. 1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PH VALUE
BIOLOGICAL EFFECTS
SODIUM 22
MEMBRANE TRANSPORT
SODIUM COMPOUNDS
BLADDER
CATIONS
KINETICS
PROTONS
TOADS
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CHARGED PARTICLES
ELEMENTARY PARTICLES
FERMIONS
HADRONS
IONS
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUCLEONS
ODD-ODD NUCLEI
ORGANS
RADIOISOTOPES
SODIUM ISOTOPES
URINARY TRACT
VERTEBRATES
YEARS LIVING RADIOISOTOPES
551001* - Physiological Systems- Tracer Techniques