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.
Pflugers Arch
1996 Jan 01;4313:379-87. doi: 10.1007/bf02207275.
Show Gene links
Show Anatomy links
Inhibition of calmodulin expression prevents low-pH-induced gap junction uncoupling in Xenopus oocytes.
Peracchia C
,
Wang X
,
Li L
,
Peracchia LL
.
???displayArticle.abstract???
The relationship among intracellular pH (pHi), -log10 intracellular Ca2+ concentration (pCai) and gap junctional conductance, the participation of Ca2+ stores, and the role of calmodulin in channel regulation have been studied in Xenopus oocytes, expressing the native connexin (Cx38), exposed to external solutions bubbled with 100% CO2. The time courses of pHi [measured with 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorscein (BCECF)], pCai (measured with the membrane-associated fura-C18) and junctional conductance (measured with a double voltage-clamp protocol) were compared. The data obtained confirm previous evidence for a closer relationship of junctional conductance with pCai than with pHi. Evidence for an inhibitory effect of intracellularly injected ruthenium red or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) on CO2-induced uncoupling, coupled to negative results with Ca2+-free external solutions, point to a low-pHi -induced Ca2+ release from internal stores, likely to be primarily mitochondria. The hypothesis proposing a participation of calmodulin in channel gating was tested by studying the effects of calmodulin expression inhibition by intracellular injection of oligonucleotides antisense to the two calmodulin mRNAs expressed in the oocytes. Calmodulin mRNA was permanently eliminated in 5h. The oocytes injected with the antisense nucleotides progressively lost the capacity to uncouple with CO2 within 72 h. The effect of CO2 on junctional conductance was reduced by approximately 60% in 24 h, by approximately 76% in 48 h and by approximately 93% in 72 h. Oocytes that had lost gating sensitivity to CO2 partially recovered gating competency following calmodulin injection. The data suggest that lowered pHi uncouples gap junctions by a Ca2+- calmodulin-mediated mechanism.
Bancel,
Investigation of noncalcium interactions of fura-2 by classical and synchronous fluorescence spectroscopy.
1992, Pubmed
Bancel,
Investigation of noncalcium interactions of fura-2 by classical and synchronous fluorescence spectroscopy.
1992,
Pubmed
Cairns,
Changes in myoplasmic pH and calcium concentration during exposure to lactate in isolated rat ventricular myocytes.
1993,
Pubmed
Chafouleas,
Regulation of intracellular levels of calmodulin and tubulin in normal and transformed cells.
1981,
Pubmed
Chien,
Isolation and characterization of calmodulin genes from Xenopus laevis.
1984,
Pubmed
,
Xenbase
Chomczynski,
Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction.
1987,
Pubmed
Dash,
Selective elimination of mRNAs in vivo: complementary oligodeoxynucleotides promote RNA degradation by an RNase H-like activity.
1987,
Pubmed
,
Xenbase
De Mello,
Effect of intracellular injection of calcium and strontium on cell communication in heart.
1975,
Pubmed
Etter,
Detection of changes in near-membrane Ca2+ concentration using a novel membrane-associated Ca2+ indicator.
1994,
Pubmed
Fujimoto,
Ultracytochemistry of calmodulin binding sites in myocardial cells by staining of frozen thin sections with colloidal gold-labeled calmodulin.
1989,
Pubmed
Gambassi,
Effects of acidosis on resting cytosolic and mitochondrial Ca2+ in mammalian myocardium.
1993,
Pubmed
Gunter,
Mitochondrial calcium transport: physiological and pathological relevance.
1994,
Pubmed
Hertzberg,
Liver gap junctions and lens fiber junctions: comparative analysis and calmodulin interaction.
1982,
Pubmed
Lazrak,
Gap junction gating sensitivity to physiological internal calcium regardless of pH in Novikoff hepatoma cells.
1993,
Pubmed
Lea,
Carbon dioxide or bicarbonate ions release Ca2+ from internal stores in crustacean myofibrillar bundles.
1981,
Pubmed
Leonard,
Ca channels induced in Xenopus oocytes by rat brain mRNA.
1987,
Pubmed
,
Xenbase
Loewenstein,
Permeability of membrane junctions.
1966,
Pubmed
Peracchia,
Effects of caffeine and ryanodine on low pHi-induced changes in gap junction conductance and calcium concentration in crayfish septate axons.
1990,
Pubmed
Peracchia,
Calmodulin-like proteins and communicating junctions. Electrical uncoupling of crayfish septate axons is inhibited by the calmodulin inhibitor W7 and is not affected by cyclic nucleotides.
1987,
Pubmed
Peracchia,
Is calmodulin involved in the regulation of gap junction permeability?
1983,
Pubmed
,
Xenbase
Peracchia,
Communicating junctions and calmodulin: inhibition of electrical uncoupling in Xenopus embryo by calmidazolium.
1984,
Pubmed
,
Xenbase
Peracchia,
Increase in gap junction resistance with acidification in crayfish septate axons is closely related to changes in intracellular calcium but not hydrogen ion concentration.
1990,
Pubmed
Pressler,
Intracellular pH and cell-to-cell transmission in sheep Purkinje fibers.
1989,
Pubmed
Ramón,
Gap junction channel modulation--a physiological viewpoint.
1986,
Pubmed
Rose,
Permeability of cell junction depends on local cytoplasmic calcium activity.
1975,
Pubmed
Spray,
Gap junctional conductance is a simple and sensitive function of intracellular pH.
1981,
Pubmed
Toyama,
Ca(2+)-calmodulin mediated modulation of the electrical coupling of ventricular myocytes isolated from guinea pig heart.
1994,
Pubmed
Turin,
Carbon dioxide reversibly abolishes ionic communication between cells of early amphibian embryo.
1977,
Pubmed
,
Xenbase
Turin,
Intracellular pH in early Xenopus embryos: its effect on current flow between blastomeres.
1980,
Pubmed
,
Xenbase
Ziegelstein,
Modulation of calcium homeostasis in cultured rat aortic endothelial cells by intracellular acidification.
1993,
Pubmed
Zimmer,
Topological analysis of the major protein in isolated intact rat liver gap junctions and gap junction-derived single membrane structures.
1987,
Pubmed
