Fig. 6. Acceleration of membrane fission kinetics by glucose-dependent Ca²⁺ entry in INS-1 cells. Experiments were performed in the cell-attached configuration. In the bath, Ca²⁺ was absent and glucose was varied between 0 and 10 mM. In the patch-pipette, Ca²⁺ was varied and channel inhibitors were included as indicated. Changes in fission pore conductance (G_p) were fit with single exponential decay functions. (A,B) With 2.6 mM Ca²⁺ in the patch-pipette, glucose stimulation accelerated the kinetics of membrane fission, indicated by a more rapid decrease in fission pore conductance and a faster fission pore time constant (). This glucose-dependent acceleration was prevented by removal of Ca²⁺ from the patch-pipette, but was not further increased when 10 mM Ca²⁺ was present. (C,D) In the presence of 10 mM glucose, the acceleration of membrane fission observed with 2.6 mM Ca²⁺ present in the patch-pipette was prevented by inclusion of the L-type Ca²⁺ channel inhibitor isradipine (2 µM) or the R-type Ca²⁺ channel inhibitor SNX-482 (100 nM). *, P<0.05.