Publication Date:
1981-02-13
Description:
The pH of the cytoplasm (pHt) measured with pH-sensitive microelectrodes in cleavage-stage blastomeres of amphibian (Ambystoma) and teleost (Fundulus) embryos is about 7.7. In electrotonically coupled cell pairs, junctional conductance is rapidly and reversibly reduced by acidification of the cytoplasm. The relation between junctional conductance and pHi is the same for increasing and decreasing pH and is independent of the rate of change over a wide range. The relation is well fitted by a Hill curve with K = 50 nM (pK = 7.3) and n = 4 to 5. The closure of gap junction channels at low pHi appears to be a cooperative process involving several charged sites. The absence of hysteresis and identity of effects for fast and slow pHi changes implies that protons act directly on the channel macromolecules and not through an intermediate in the cytoplasm.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Spray, D C -- Harris, A L -- Bennett, M V -- HD-02428/HD/NICHD NIH HHS/ -- NS-07512/NS/NINDS NIH HHS/ -- NS-12627/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1981 Feb 13;211(4483):712-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6779379" target="_blank"〉PubMed〈/a〉
Keywords:
Ambystoma/embryology
;
Animals
;
Carbon Dioxide
;
*Cell Communication
;
Cytoplasm/*physiology
;
Electric Conductivity
;
*Hydrogen-Ion Concentration
;
Intercellular Junctions/*physiology
;
Killifishes/embryology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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