Biophysical properties of gap junctions between freshly dispersed pairs of mouse pancreatic beta cells

M. Perez-Armendariz, C. Roy, David C. Spray, Michael V. L. Bennett

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Abstract

Coupling between beta cells through gap junctions has been postulated as a principal mechanism of electrical synchronization of glucose-induced activity throughout the islet of Langerhans. We characterized junctional conductance between isolated pairs of mouse pancreatic beta cells by whole-cell recording with two independent patch-clamp circuits. Most pairs were coupled (67%, n = 155), although the mean junctional conductance (g(j)) (215 ± 110 pS) was lower than reported in the other tissues. Coupling could be recorded for long periods, up to 40 min. Voltage imposed across the junctional or nonjunctional membranes had no effect on g(j). Up to several hours of treatment to increase intracellular cAMP levels did not affect g(j). Electrically coupled pairs did not show transfer of the dye Lucifer yellow. Octanol (2 mM) reversibly decreased g(j). Lower concentrations of octanol (0.5 mM) and heptanol (0.5 mM) than required to uncouple beta cells decreased voltage-dependent K+ and Ca2+ currents in nonjunctional membranes. Although g(j) recorded in these experiments would be expected to be provided by current flowing through only a few channels of the unitary conductance previously reported for other gap junctions, no unitary junctional currents were observed even during reversible suppression of g(j) by octanol. This result suggests either that the single channel conductance of gap junction channels between beta cells is smaller than in other tissues (<20 pS) or that the small mean conductance is due to transitions between open and closed states that are too rapid or too slow to be resolved.

Original languageEnglish (US)
Pages (from-to)76-92
Number of pages17
JournalBiophysical Journal
Volume59
Issue number1
StatePublished - 1991

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Gap Junctions
Insulin-Secreting Cells
Octanols
Heptanol
Membranes
Patch-Clamp Techniques
Islets of Langerhans
Coloring Agents
Glucose

ASJC Scopus subject areas

  • Biophysics

Cite this

Biophysical properties of gap junctions between freshly dispersed pairs of mouse pancreatic beta cells. / Perez-Armendariz, M.; Roy, C.; Spray, David C.; Bennett, Michael V. L.

In: Biophysical Journal, Vol. 59, No. 1, 1991, p. 76-92.

Research output: Contribution to journalArticle

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