Figure 2
From: Prostaglandin E2 potentiation of P2X3 receptor mediated currents in dorsal root ganglion neurons
Characteristics of PGE2 actions.
(A) Time course of PGE2 effects on fast ATP currents. ATP pulses were applied to the recorded cell every 2 min. After ATP responses reached a steady state, 1 μM PGE2 was applied to the bath. The fast ATP response was increased by 48% [IATP (with PGE2)/IATP = 1.48 ± 0.07, n = 6] two min later and the increase reached a peak level [IATP (with PGE2)/IATP = 1.90 ± 0.11] 10 min after PGE2 application. Numbers in the graph correspond to the original traces shown above.
(B) Bar graphs are the pooled data from 5 cells (* P < 0.05).
(C) PGE2 does not change the affinity of ATP for P2X3 receptors. Fast ATP currents were measured at different ATP concentrations in control and in 1 μM PGE2. For the purpose of normalization among cells, the responses to 10 μM ATP in control solution in all of the cells were measured. Each data point was obtained from studies of 4–6 cells. The data points at 0.01 and 0.1 μM ATP for control and PGE2 groups overlapped. The dose-response curves were fit by the Hill equation with Hill coefficient = 1. For control, EC50 = 2.02 ± 0.4 μM. For PGE2, EC50 = 2.77 ± 0.58 μM. PGE2 treatment does not alter ATP affinities for P2X receptors, although it greatly enhances peak ATP responses.