Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Ionic basis of membrane potential in developing ectoderm of the Xenopus blastula.
Baud C
.
???displayArticle.abstract???
1. The membrane potential and permeabilities of blastomeres isolated from the ectoderm of stage 6-10 Xenopus blastulae have been investigated. The increase in membrane potential between stages 6 and 9, reported previously in intact embryos, is not clearly apparent in isolated cells. However, marked differences were observed between early and late stages. 2. The membrane specific resistance was high at all stages (100-300 k omega cm2) and increased from stage 6 to stage 9. This specific resistance is much higher than previous estimates of the permeability of newly formed membrane after fertilization and very different from values reported for differentiated cells. 3. The membrane Na-K pump activity has been measured at all stages by applying ouabain to the cells (10(-4) to 10(-3) M). The pump rate per unit surface area, calculated as the ratio of the ouabain-sensitive part of the resting potential to the specific resistance, decreased from stage 7 (about 0.19 microA/microF) to stage 9 (about 0.04 microA/microF). 4. The ouabain-insensitive part of the resting potential increased from stage 6 to 9. At all stages, the blastomeres were permeable primarily to K+; blastomeres at stage 9 were more sensitive to change of external K+ than at stage 7, suggesting an increase in K+ selectivity. 5. The membrane potential was very sensitive to external pH at all stages. External protons appeared to block the permeability to K+. At low pH, it was possible to demonstrate some permeability of early blastomeres to Na+. 6. At variable times after impalement, cells underwent an increase in K+ permeability of 5- to 10-fold. This seems to be due to ion leak from the intracellular electrode. 7. This dual membrane state was observed at all stages and it may explain some of the earlier reports of high K+ permeability.
Baud,
Changes in membrane hydrogen and sodium conductances during progesterone-induced maturation of Ambystoma oocytes.
1984, Pubmed
Baud,
Changes in membrane hydrogen and sodium conductances during progesterone-induced maturation of Ambystoma oocytes.
1984,
Pubmed
Cross,
A fast block to polyspermy in frogs mediated by changes in the membrane potential.
1980,
Pubmed
DiCaprio,
On the mechanism of electrical coupling between cells of early Xenopus embryos.
1976,
Pubmed
,
Xenbase
Gillespie,
The distribution of small ions during the early development of Xenopus laevis and Ambystoma mexicanum embryos.
1983,
Pubmed
,
Xenbase
Grey,
An electrical block is required to prevent polyspermy in eggs fertilized by natural mating of Xenopus laevis.
1982,
Pubmed
,
Xenbase
Grinstein,
Responses of lymphocytes to anisotonic media: volume-regulating behavior.
1984,
Pubmed
Guthrie,
Patterns of junctional communication in the early amphibian embryo.
,
Pubmed
,
Xenbase
Kline,
Ion currents and membrane domains in the cleaving Xenopus egg.
1983,
Pubmed
,
Xenbase
Lee,
Observations on intracellular pH during cleavage of eggs of Xenopus laevis.
1981,
Pubmed
,
Xenbase
Loewenstein,
Quantum jumps of conductance during formation of membrane channels at cell-cell junction.
1978,
Pubmed
,
Xenbase
Messenger,
The function of the sodium pump during differentiation of amphibian embryonic neurones.
1979,
Pubmed
,
Xenbase
Moreau,
[Early changes in the electric properties of the oocyte plasma membrane of Xenopus laevis during the reinitiation of meiosis induced by progesterone, para chloromercuribenzoate (PCMB) or the ionophore A 23187].
1976,
Pubmed
,
Xenbase
Newport,
A major developmental transition in early Xenopus embryos: I. characterization and timing of cellular changes at the midblastula stage.
1982,
Pubmed
,
Xenbase
Palmer,
Some bio-electric parameters of early Xenopus embryos.
1970,
Pubmed
,
Xenbase
Schlichter,
Spontaneous action potentials produced by Na and Cl channels in maturing Rana pipiens oocytes.
1983,
Pubmed
Schlichter,
A role for action potentials in maturing Rana pipiens oocytes.
1983,
Pubmed
Slack,
Intracellular and intercellular potentials in the early amphibian embryo.
1973,
Pubmed
,
Xenbase
Slack,
Properties of surface and junctional membranes of embryonic cells isolated from blastula stages of Xenopus laevis.
1975,
Pubmed
,
Xenbase
Smith,
Cell lineage labels and region-specific markers in the analysis of inductive interactions.
1985,
Pubmed
,
Xenbase
Spitzer,
Voltage- and stage-dependent uncoupling of Rohon-Beard neurones during embryonic development of Xenopus tadpoles.
1982,
Pubmed
,
Xenbase
Spray,
Equilibrium properties of a voltage-dependent junctional conductance.
1981,
Pubmed
,
Xenbase
Turin,
Intracellular pH in early Xenopus embryos: its effect on current flow between blastomeres.
1980,
Pubmed
,
Xenbase
Turin,
Electrogenic sodium pumping in Xenopus blastomeres: apparent pump conductance and reversal potential.
1984,
Pubmed
,
Xenbase
Wallace,
Maturation of Xenopus oocytes. II. Observations on membrane potential.
1977,
Pubmed
,
Xenbase
Webb,
Fertilization potential and electrical properties of the Xenopus laevis egg.
1985,
Pubmed
,
Xenbase
Webb,
A comparative study of the membrane potential from before fertilization through early cleavage in two frogs, Rana pipiens and Xenopus laevis.
1985,
Pubmed
,
Xenbase
Woodward,
Electrical signs of new membrane production during cleavage of Rana pipiens eggs.
1968,
Pubmed
de Laat,
New membrane formation during cytokinesis in normal and cytochalasin B-treated eggs of Xenopus laevis. II. Electrophysiological observations.
1974,
Pubmed
,
Xenbase
de Laat,
Intracellular ionic distribution, cell membrane permeability and membrane potential of the Xenopus egg during first cleavage.
1974,
Pubmed
,
Xenbase