Figure 5. Kinetics of mutated hP2X₇ receptors.

A and B, examples of ATP-activated currents of His-hP2X₇ and His-hP2X₇ΔC, respectively. The relation of the slope of the linearly activating current to the steady-state amplitude of the exponentially activating current, s/I_act,∞, was calculated as 0.019 and 0.0006 s⁻¹ and the relation of the initial amplitudes of the fast and slow deactivating current, I_deact,2/I_deact,1, was determined as 0.4 and 0.0 for A and B, respectively. For further explanation, see Fig. 1. C, relation of the slope of the linearly (s) to the exponentially (I_act,∞) activating current approximated according to eqn (1). D, relation of the amplitudes of the fast (I_deact,2) to the slow (I_deact,1) deactivating current as fitted by eqn (2). Currents were activated by 1 mm ATP in divalent-free oocyte Ringer solution. The means (from 9 to 25 oocytes) are statistically different in C and D.