Figure/Graphic 5: Kalziumkanal - Mibefradil
Left panel: Inhibition of volume-activated Cl- currents by mibefradil. a: Activation of the volume-sensitive Cl- current ICl,vol by challenging the cell with a 27 % hypotonic solution. Mibefradil induced a fast and reversible block of ICl,vol. b: At the times indicated, I-V curves were depicted. Reversal potential was approximately at the expected ECl= -16 mV. c: Concentrationresponse curve of the inhibitory action of mibefradil on ICl,vol. Right panel: High-affinity block of Ca2+ activated Cl- channels by mibefradil. a: A CPAE cell was loaded with a Ca2+-solution buffered at 500 nM after breaking the membrane. Elevation of [Ca2+]i activated a Cl- current ICl,Ca. This current was probed by application of voltage ramps. From these ramps, the current can be measured at any potential. Shown is the current activation at +100 mV. Application of 10 microM mibefradil induced a fast and reversible block of ICl,Ca. b: At the times indicated in A, I-V curves were depicted; 1) shows the fully activated Cl- current, 2) the blocked current after application of mibefradil. c: Concentration-response curve of the inhibitory action of mibefradil.