Figure 5
From: Prostaglandin E2 potentiation of P2X3 receptor mediated currents in dorsal root ganglion neurons
PKA mediates PGE2-induced increases in ATP responses. (A) Effects of the PKA inhibitor, H89. Treatment with H89 (1 μM) reduced ATP currents moderately. In the presence of H89, PGE2 could no longer increase ATP currents. The block of H89 was reversed rather slowly. After washout of H89 for 35 min, the PGE2 potentiating effect returned to the control levels. (B) Effects of the specific membrane impermeant inhibitor PKA-inhibitor (6–22) (PKA-I). PKA-I (0.2 μM) was included in the patch pipette. As the result of small diameter tip pipettes used in these experiments, PKA-I did not reach its final concentration in the cell interior several minutes after whole cell recording was established. This allowed us to obtain a few control responses to PGE2 before PKA-I became effective. With PKA-I, PGE2 no longer potentiated ATP responses. (C) Effects of the PKC inhibitor, Bis. Pretreatment of the cell with Bis (1 μM) did not affect the potentiating effect of PGE2. (D) Average effects of PGE2, (PGE2+ H89), (PGE2+PKA-I) and (PGE2+Bis). For each protein kinase inhibitor, the effects of PGE2 and (PGE2+ inhibitor) were examined in the same cell. For H89, IATP (PGE2-H)/IATP = 1.52 ± 0.08; IATP (PGE2-H+H89)/IATP = 0.94 ± 0.06. For PKA-I, IATP (PGE2-P)/IATP = 1.48 ± 0.09; IATP (PGE2-P+PKA-I)/IATP = 0.92 ± 0.05. For Bis, IATP (PGE2-B)/IATP = 1.46 ± 0.07, IATP (PGE2-B+Bis)/IATP = 1.42 ± 0.08. Five cells were tested in each group (* P < 0.05, NS = not significant).