Figure 5
Phalloidin prevents BVT.12777 activation of K ATP A, current clamp record of a CRI-G1 cell dialysed with 5 mM MgATP and 10 μM phalloidin. Application of BVT.12777 (200 μM) had no effect on the membrane potential of the cell (-41 mV) in the presence of phalloidin. B, continuous single channel currents recorded from an inside-out patch at a holding potential of -40 mV. Application of 100 μM MgATP reversibly inhibited Nf.Po from 1.25 to 0.02. Addition of 10 μM phalloidin and subsequently 100 μM BVT.12777, in the presence of 100 μM MgATP, to the cytoplasmic aspect of the patch resulted in no effect on KATP, with Nf.Po values of 0.01 and 0.03 respectively. C, current clamp record of a CRI-G1 cell dialysed with 5 mM MgATP and 10 μM phalloidin. Application of diazoxide (200 μM) induced rapid cell membrane hyperpolarization, from -55 to -72 mV, an action reversed (to -45 mV) by tolbutamide (100 μM).