Abstract
In vertebrate embryos gap junctional conductance (gj) is reduced by transjunctional voltage (Vj) and by cytoplasmic acidification; in each case sensitivity is comparable to those of other channels gated by voltage and ligand-receptor binding. We show here that the mechanisms by which Vj and intracellular pH (pHi) gate gj are apparently independent. Partial reduction of gj by lowering pHi neither attenuates nor enhances further reduction by Vj. Certain drugs irreversibly (glutaraldehyde, 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline) or reversibly (retinoic acid) abolish dependence of gj on pHi without appreciably affecting kinetic properties of voltage dependence or the shape of the steady-state Vj-gj relation. These findings suggest that the mechanisms by which pHi and Vj act on the gap junction are at least partially distinct and presumably involve separate regions of the junctional macromolecules.
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- Bennett M. V. Physiology of electrotonic junctions. Ann N Y Acad Sci. 1966 Jul 14;137(2):509–539. doi: 10.1111/j.1749-6632.1966.tb50178.x. [DOI] [PubMed] [Google Scholar]
- Bennett M. V., Spira M. E., Pappas G. D. Properties of electrotonic junctions between embryonic cells of Fundulus. Dev Biol. 1972 Dec;29(4):419–435. doi: 10.1016/0012-1606(72)90082-6. [DOI] [PubMed] [Google Scholar]
- Guy H. R. A structural model of the acetylcholine receptor channel based on partition energy and helix packing calculations. Biophys J. 1984 Jan;45(1):249–261. doi: 10.1016/S0006-3495(84)84152-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Obaid A. L., Socolar S. J., Rose B. Cell-to-cell channels with two independently regulated gates in series: analysis of junctional conductance modulation by membrane potential, calcium, and pH. J Membr Biol. 1983;73(1):69–89. doi: 10.1007/BF01870342. [DOI] [PubMed] [Google Scholar]
- Schuetze S. M., Goodenough D. A. Dye transfer between cells of the embryonic chick lens becomes less sensitive to CO2 treatment with development. J Cell Biol. 1982 Mar;92(3):694–705. doi: 10.1083/jcb.92.3.694. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spray D. C., Bennett M. V. Physiology and pharmacology of gap junctions. Annu Rev Physiol. 1985;47:281–303. doi: 10.1146/annurev.ph.47.030185.001433. [DOI] [PubMed] [Google Scholar]
- Spray D. C., Harris A. L., Bennett M. V. Equilibrium properties of a voltage-dependent junctional conductance. J Gen Physiol. 1981 Jan;77(1):77–93. doi: 10.1085/jgp.77.1.77. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spray D. C., Harris A. L., Bennett M. V. Gap junctional conductance is a simple and sensitive function of intracellular pH. Science. 1981 Feb 13;211(4483):712–715. doi: 10.1126/science.6779379. [DOI] [PubMed] [Google Scholar]
- Spray D. C., Nerbonne J., Campos de Carvalho A., Harris A. L., Bennett M. V. Substituted benzyl acetates: a new class of compounds that reduce gap junctional conductance by cytoplasmic acidification. J Cell Biol. 1984 Jul;99(1 Pt 1):174–179. doi: 10.1083/jcb.99.1.174. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spray D. C., White R. L., de Carvalho A. C., Harris A. L., Bennett M. V. Gating of gap junction channels. Biophys J. 1984 Jan;45(1):219–230. doi: 10.1016/S0006-3495(84)84150-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tickle C., Alberts B., Wolpert L., Lee J. Local application of retinoic acid to the limb bond mimics the action of the polarizing region. Nature. 1982 Apr 8;296(5857):564–566. doi: 10.1038/296564a0. [DOI] [PubMed] [Google Scholar]
- White R. L., Spray D. C., Campos de Carvalho A. C., Wittenberg B. A., Bennett M. V. Some electrical and pharmacological properties of gap junctions between adult ventricular myocytes. Am J Physiol. 1985 Nov;249(5 Pt 1):C447–C455. doi: 10.1152/ajpcell.1985.249.5.C447. [DOI] [PubMed] [Google Scholar]