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This Article Full Text Full Text (PDF) All Versions of this Article: 288/5/E948    most recent 00216.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Moreno, A. P. Articles by Pérez-Armendariz, E. M. Search for Related Content PubMed PubMed Citation Articles by Moreno, A. P. Articles by Pérez-Armendariz, E. M.

Biophysical evidence that connexin-36 forms functional gap junction channels between pancreatic mouse -cells

¹Krannert Institute of Cardiology, Indiana School of Medicine, Indianapolis, Indiana; ²Section of Hematology/Oncology, Department of Pediatrics, University of Chicago, Chicago, Illinois; and ³Facultad de Medicina, Departmento de Medicina Experimental, Unidad de Investigación, Enseñanza y Comunicación Ensalud Sexual y Reproductiva, Universidad Nacional Autónoma de México, Mexico City, Mexico

Submitted 25 May 2004 ; accepted in final form 15 December 2004

Connexin-36 (Cx36) is the only gap junction protein that has been unambiguously identified in rodent pancreatic -cells. However, properties of gap junction channel unitary currents between -cells remain unrevealed. To address whether Cx36 forms functional channels in -cells, we characterized biophysical properties of macro- and microscopic junctional currents recorded from dual whole cell voltage clamp isolated pairs of dispersed mouse -cells. Electrical coupling was recorded in 80% of cell pairs with a junctional conductance (g_j) of 355 ± 45 pS (n = 20). Transjunctional voltage dependence was identified in three of seven cell pairs with high-input membrane resistances. Normalized steady-state g_j (G_j) and transjunctional-voltage relation were well described by a two-state Boltzmann equation [maximal conductance (G_max) = 1.0, voltage-insensitive conductance (G_min) = 0.3 and 0.28, voltage gating sensitivity (A) = 0.21 and 0.23, and voltage at which one-half of the initial voltage-dependent conductance was reached (V_o) = –85 and 87 mV for negative and positive potentials, respectively]. Halothane reversibly uncoupled -cell pairs, and, during recovery, unitary conductances of 5–10 pS were recorded while using patch pipettes containing mainly CsCl. Although these properties are similar to those previously described for Cx36 channels in mammalian cell systems, we found that -cell junctional currents were insensitive to quinine. Cx36 transcript and protein expression in islets and freshly dispersed cell preparations was confirmed by RT-PCR and immunofluorescence. In conclusion, biophysical properties of junctional channels between -cells are similar but not identical to those previously described for homomeric Cx36 channels. Cell type-specific mechanisms that may account for these differences are discussed.

islets of Langerhans; insulin; connexin; intercellular communication

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