Fig. 2.
Permeability transition of P2X7 receptor.
A transient stimulation with ATP causes the opening of the P2X7 channel and the concomitant Ca++ and Na+ influx and K+ efflux. However, upon sustained stimulation with ATP, the P2X7 receptor undergoes a transition that generates a reversible membrane pore permeable to several low-molecular-weight hydrophylic solutes (Fura-2/FA, Fura-2 free acid; LY, lucifer yellow; EB, ethidium bromide) and to nucleotides.
