Biomaterial Database

Biophysical properties of gap junctions between freshly dispersed pairs of mouse pancreatic beta cells. 1991

M Pérez-Armendariz, and C Roy, and D C Spray, and M V Bennett

Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461.

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 (gj) (215 +/- 110 pS) was lower than reported in 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 gj. Up to several hours of treatment to increase intracellular cAMP levels did not affect gj. Electrically coupled pairs did not show transfer of the dye Lucifer yellow. Octanol (2 mM) reversibly decreased gj. 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 gj 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 gj by octanol. This result suggests either that the single channel conductance of gap junction channels between beta cells is smaller than in other tissues (less than 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.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D007515	Islets of Langerhans	Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN.	Islands of Langerhans,Islet Cells,Nesidioblasts,Pancreas, Endocrine,Pancreatic Islets,Cell, Islet,Cells, Islet,Endocrine Pancreas,Islet Cell,Islet, Pancreatic,Islets, Pancreatic,Langerhans Islands,Langerhans Islets,Nesidioblast,Pancreatic Islet
D007546	Isoquinolines	A group of compounds with the heterocyclic ring structure of benzo(c)pyridine. The ring structure is characteristic of the group of opium alkaloids such as papaverine. (From Stedman, 25th ed)
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008815	Mice, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.	Inbred Mouse Strains,Inbred Strain of Mice,Inbred Strain of Mouse,Inbred Strains of Mice,Mouse, Inbred Strain,Inbred Mouse Strain,Mouse Inbred Strain,Mouse Inbred Strains,Mouse Strain, Inbred,Mouse Strains, Inbred,Strain, Inbred Mouse,Strains, Inbred Mouse
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.