Fig. 5.

[K⁺]_o-dependent decreases in ROMK current. TPNQ-sensitive outward currents were measured after maintaining the whole-cell clamp for 2 min with [K⁺]_o = 1 or 10 mM. Differences in current persisted with pH 8.0 in the pipette solution and with FVPP pipette solution. Inclusion of 0.5 mM DTT in the pipette solution or preincubation of tubules with U73122 (5 μM) abolished the differences. Data represent means ± SE for 17 pairs of cells (control), 13 pairs (pH 8), 9 pairs (FVPP), 18 pairs (DTT), or 11 pairs (U73122). *P < 0.05, significant difference.