OSCILLATION OF GAP JUNCTION ELECTRICAL COUPLING IN THE MOUSE PANCREATIC-ISLETS OF LANGERHANS

1. Pancreatic beta-cells oscillate synchronously when grouped in islet s. Coupling seems essential to maintain this oscillatory behaviour, as isolated cells are unable to oscillate. This allows the islet to be u sed as a model system for studying the role of coupling in the generat ion of oscillatory patterns. 2. Pairs of beta-cells were intracellular ly recorded in islets. beta-Cells oscillated synchronously. Propagated voltage deflections were observed as a function of glucose concentrat ion and of the distance between the recording electrodes. Space consta nts were smaller in the silent than in the active phases, suggesting a higher intercellular connection in the active phases. 3. Coupling coe fficients and estimated coupling conductances were larger in the activ e than in the silent phases. 4. Coupling coefficients and coupling con ductances changed dynamically and in phase with the membrane potential oscillations, pointing to an active modulation of the gap junctions. 5. We hypothesize a role for coupling in the generation of the oscilla tory events, providing different levels of permeability dependent on t he state of conductance during the oscillatory phases.