Fig. 4.
The inwardly rectifying current induced by DMPP is completely blocked by barium (100 μm). A, A graph of the whole-cell current [prazosin (1 μm) was present at all times] versus the membrane potential at which it was measured is shown with two curves. Thecontrol curve was obtained before exposure to DMPP (15 μm), and the curve labeled DMPP was obtained during the exposure. B, The curve shown was calculated by subtraction of the control curve from theDMPP curve to give the current generated by DMPP. An inward rectification of the current similar to that evoked by 5-HT1A agonists is apparent. C,D, The two graphs are similar to those inA and B except that barium (100 μm) was present. The current induced by DMPP was completely blocked.