Fig. 6.

Kinetics of Ba²⁺ block in Kir2.1/Kir2.2 channels. Kinetics of Ba²⁺ block was studied in outside-out patches at high symmetrical K⁺ in the presence of 10 μM Ba²⁺ and at −100-mV membrane potential. a Examples of current traces for a Kir2.1-1-1-1 channel (top) and a Kir2.1-1-2-2 channel (bottom), both of which are fit (dashed line) with a single-exponential function. For clarity, only the first part of the 2-s current trace is shown. b Two recordings from two separate outside-out patches of Kir2.2-2-2-2 channels. Top, a single-exponential function does not fit well the current trace; however, in the recording from the other patch (bottom), a single-exponential function fits the current trace adequately. c The τ _block values for each construct. Insert, averaged τ _block values for channels with the same stoichiometries: 1, Kir2.1 Mono/1-1-1-1; 2, 2-1-1-1/1-1-1-2/1-2-1-1; 3, 1-1-2-2/1-2-1-2; 4, 1-2-2-2; and 5, Kir2.2 Mono/Kir2-2-2-2