Fig. 6.

Uroguanylin inhibits H⁺-ATPase-dependent pH recovery in MDCK-C11 cells by a PKG-dependent pathway. MDCK-C11 cells were treated with 1 μM UGN or 8br-cGMP in the presence of EIPA (NHE1 inhibitor) and Schering (SCH, H/K-ATPase inhibitor), and/or KT5823 (KT, PKG inhibitor) diluted in 0 Na solution, after intracellular acidification by means of the ammonium pulse technique. The initial rates of pHi recovery (pH U/min) were calculated from the curves by linear regression analysis (A). B: plotted rates of hydrogen extrusion, which was obtained from the product of dpHi/dt and intracellular buffer capacity, βi, of the average pHi of the experimental groups (pHi 6.5). UGN significantly inhibits H⁺-ATPase-dependent pH_i recovery and hydrogen extrusion in MDCK-C11 cells. Number of experiments is indicated in the bars. *P < 0.05 vs. EIPA + SCH.