Figure 3.
(A) Continuous recording at different internal calcium concentrations from a representative inside-out patch containing several hIK1 channels. Decreasing the calcium concentration from 0.8 to 0.6 μM decreased channel activity. Channel activity ceased when calcium was removed and returned following reapplication of 0.6 μM calcium. Gaps represent breaks in the continuously acquired recording. (B) Channel activity from a representative patch recorded in the presence of 0.4 μM calcium at −80, −60, −40, and 60 mV. The patch contained more than one channel, and double openings are apparent. (C) Single channel current–voltage relationship for the patch presented in B. Data points were derived from fitting amplitude histograms at each membrane potential; a representative histogram (−40 mV) and fit are shown as an Inset. Linear regression fitting of the current–voltage relationship between −60 and −100 mV yielded a single channel conductance of 42 pS.