Fig. 9.

rTASK single-channel properties recorded from outside-out patches. A, Single-channelI–V relations. The recordings were made with 150 mm K⁺ in the recording pipette and bath solutions of 150 mm NaCl (circles;n = 7), a mixture of 75 mmNa⁺ with 75 mm K⁺(triangles; n = 2), and 150 mm K⁺ (squares;n = 4). In the presence of symmetrical 150 mm K⁺, the I–V relation was best fit to a linear function. Data in the other conditions were fit with third degree polynomial functions, which illustrates the pattern of outward rectification. The unitary current was measured as the amplitude of the current from the closed channel level to a cursor positioned in the center of the open channel noise. Error bars indicate SD of the mean. B, Independence of the open probability of single rTASK channels from the patch potential. The open probabilities are the means from outside-out patches (n = 4) recorded with a bath solution of 150 mm NaCl. Individual values were calculated by setting the single-channel amplitude to unity and integrating records from 30 sec data segments at each voltage. Error bars indicate SDs.