Effects of blockade of IP3-sensitive pathway on BNP-induced reduction of GABA currents. A, After internal infusion of 5 mg/ml heparin for 5 min, 50 nm BNP still reduced the GABA current. B, Bar chart showing that 50 nm BNP reduced the GABA current during internal infusion of heparin. C, Internal infusion of 20 μm xestospongin-C (Xe-C) increased the GABA current and did not block the BNP (50 nm)-induced reduction. D, Bar chart showing that internal infusion of xestospongin-C (Xe-C) increased the GABA current, compared with the initial value recorded just after membrane rupture. Application of 50 nm BNP induced a reduction of the GABA current in the presence of 20 μm xestospongin-C. Error bars represent SEM.