Permeability of homotypic and heterotypic gap junction channels formed of cardiac connexins mCx30.2, Cx40, Cx43, and Cx45

Mindaugas Rackauskas, Vytautas Verselis, Feliksas F. Bukauskas

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Abstract

We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (Pγ). All homotypic channels were permeable to the anionic monovalent dye Alexa Fluor-350 (AF350), but mCx30.2 channels exhibited a significantly lower Pγ than the others. The anionic divalent dye Lucifer yellow (LY) remained permeant in Cx40, Cx43, and Cx45 channels, but transfer through mCx30.2 channels was not detected. Heterotypic channels generally exhibited Pγ values that were intermediate to the corresponding homotypic channels. Pγ values of mCx30.2/Cx40, mCx30.2/Cx43, or mCx30.2/Cx45 heterotypic channels for AF350 were similar and approximately twofold higher than Pγ values of mCx30.2 homotypic channels. Permeabilities for cationic dyes were assessed only qualitatively because of their binding to nucleic acids. All homotypic and heterotypic channel configurations were permeable to ethidium bromide and 4,6-diamidino-2- phenylindole. Permeability for propidium iodide was limited only for GJ channels that contain at least one mCx30.2 hemichannel. In summary, we have demonstrated that Cx40, Cx43, and Cx45 are permeant to all examined cationic and anionic dyes, whereas mCx30.2 demonstrates permeation restrictions for molecules with molecular mass over ∼400 Da. The ratio of single-channel conductance to permeability for AF350 was ∼40- to 170-fold higher for mCx30.2 than for Cx40, Cx43, and Cx45, suggesting that mCx30.2 GJs are notably more adapted to perform electrical rather than metabolic cell-cell communication.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume293
Issue number3
DOIs
StatePublished - Sep 2007

Fingerprint

Connexin 43
Gap Junctions
Permeability
Coloring Agents
Ethidium
Propidium
Fluorescent Dyes
Cell Communication
Nucleic Acids
Rodentia
connexin 40
Alexa 350

Keywords

  • 4,6-diamidino-2-phenylindole
  • Connexin
  • Dye
  • Gap junctions
  • Lucifer yellow

ASJC Scopus subject areas

  • Physiology

Cite this

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title = "Permeability of homotypic and heterotypic gap junction channels formed of cardiac connexins mCx30.2, Cx40, Cx43, and Cx45",
abstract = "We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (Pγ). All homotypic channels were permeable to the anionic monovalent dye Alexa Fluor-350 (AF350), but mCx30.2 channels exhibited a significantly lower Pγ than the others. The anionic divalent dye Lucifer yellow (LY) remained permeant in Cx40, Cx43, and Cx45 channels, but transfer through mCx30.2 channels was not detected. Heterotypic channels generally exhibited Pγ values that were intermediate to the corresponding homotypic channels. Pγ values of mCx30.2/Cx40, mCx30.2/Cx43, or mCx30.2/Cx45 heterotypic channels for AF350 were similar and approximately twofold higher than Pγ values of mCx30.2 homotypic channels. Permeabilities for cationic dyes were assessed only qualitatively because of their binding to nucleic acids. All homotypic and heterotypic channel configurations were permeable to ethidium bromide and 4,6-diamidino-2- phenylindole. Permeability for propidium iodide was limited only for GJ channels that contain at least one mCx30.2 hemichannel. In summary, we have demonstrated that Cx40, Cx43, and Cx45 are permeant to all examined cationic and anionic dyes, whereas mCx30.2 demonstrates permeation restrictions for molecules with molecular mass over ∼400 Da. The ratio of single-channel conductance to permeability for AF350 was ∼40- to 170-fold higher for mCx30.2 than for Cx40, Cx43, and Cx45, suggesting that mCx30.2 GJs are notably more adapted to perform electrical rather than metabolic cell-cell communication.",
keywords = "4,6-diamidino-2-phenylindole, Connexin, Dye, Gap junctions, Lucifer yellow",
author = "Mindaugas Rackauskas and Vytautas Verselis and Bukauskas, {Feliksas F.}",
year = "2007",
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journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
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TY - JOUR

T1 - Permeability of homotypic and heterotypic gap junction channels formed of cardiac connexins mCx30.2, Cx40, Cx43, and Cx45

AU - Rackauskas, Mindaugas

AU - Verselis, Vytautas

AU - Bukauskas, Feliksas F.

PY - 2007/9

Y1 - 2007/9

N2 - We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (Pγ). All homotypic channels were permeable to the anionic monovalent dye Alexa Fluor-350 (AF350), but mCx30.2 channels exhibited a significantly lower Pγ than the others. The anionic divalent dye Lucifer yellow (LY) remained permeant in Cx40, Cx43, and Cx45 channels, but transfer through mCx30.2 channels was not detected. Heterotypic channels generally exhibited Pγ values that were intermediate to the corresponding homotypic channels. Pγ values of mCx30.2/Cx40, mCx30.2/Cx43, or mCx30.2/Cx45 heterotypic channels for AF350 were similar and approximately twofold higher than Pγ values of mCx30.2 homotypic channels. Permeabilities for cationic dyes were assessed only qualitatively because of their binding to nucleic acids. All homotypic and heterotypic channel configurations were permeable to ethidium bromide and 4,6-diamidino-2- phenylindole. Permeability for propidium iodide was limited only for GJ channels that contain at least one mCx30.2 hemichannel. In summary, we have demonstrated that Cx40, Cx43, and Cx45 are permeant to all examined cationic and anionic dyes, whereas mCx30.2 demonstrates permeation restrictions for molecules with molecular mass over ∼400 Da. The ratio of single-channel conductance to permeability for AF350 was ∼40- to 170-fold higher for mCx30.2 than for Cx40, Cx43, and Cx45, suggesting that mCx30.2 GJs are notably more adapted to perform electrical rather than metabolic cell-cell communication.

AB - We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (Pγ). All homotypic channels were permeable to the anionic monovalent dye Alexa Fluor-350 (AF350), but mCx30.2 channels exhibited a significantly lower Pγ than the others. The anionic divalent dye Lucifer yellow (LY) remained permeant in Cx40, Cx43, and Cx45 channels, but transfer through mCx30.2 channels was not detected. Heterotypic channels generally exhibited Pγ values that were intermediate to the corresponding homotypic channels. Pγ values of mCx30.2/Cx40, mCx30.2/Cx43, or mCx30.2/Cx45 heterotypic channels for AF350 were similar and approximately twofold higher than Pγ values of mCx30.2 homotypic channels. Permeabilities for cationic dyes were assessed only qualitatively because of their binding to nucleic acids. All homotypic and heterotypic channel configurations were permeable to ethidium bromide and 4,6-diamidino-2- phenylindole. Permeability for propidium iodide was limited only for GJ channels that contain at least one mCx30.2 hemichannel. In summary, we have demonstrated that Cx40, Cx43, and Cx45 are permeant to all examined cationic and anionic dyes, whereas mCx30.2 demonstrates permeation restrictions for molecules with molecular mass over ∼400 Da. The ratio of single-channel conductance to permeability for AF350 was ∼40- to 170-fold higher for mCx30.2 than for Cx40, Cx43, and Cx45, suggesting that mCx30.2 GJs are notably more adapted to perform electrical rather than metabolic cell-cell communication.

KW - 4,6-diamidino-2-phenylindole

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KW - Dye

KW - Gap junctions

KW - Lucifer yellow

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U2 - 10.1152/ajpheart.00234.2007

DO - 10.1152/ajpheart.00234.2007

M3 - Article

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