Fig. 2.

Effect of PMA on ATP-induced currents mediated by expressed P2X₂ and P2X₃ receptors in X. laevis oocytes. a The electrical membrane capacitance was monitored as a measure of the oocyte surface area during sustained stimulation with PMA. Each bar represents the mean C_m±SEM calculated from the areas under the current transients elicited in 10-s intervals by five consecutive 10-mV depolarizing steps. b, c Representative current traces elicited by 10-s lasting pulses of 100 μM ATP applied in 10-min intervals to oocytes expressing the indicated P2X receptors or P2X receptor mutants. Where denoted by a black bar, oocytes were pre-incubated with 100 nM PMA before ATP was co-applied. PMA was without effect on the P2X₂ receptor-mediated current (b), but induced a marked increase of the current amplitude mediated by P2X₃ receptors (c). Gray areas indicate the duration of ATP application