Figure 3.

Bradykinin stimulates NHE activity in A498 cells.

Notes: Proton microphysiometry was performed on quiescent A498 cell monolayers as described in the Methods section. Cells were exposed to a perfusate-containing drug (100 nM BK) during the time span encompassed by the gray box. (A) BK (white circles) stimulates ECAR, whereas pretreatment with 5 μM of the NHE-1 and -2 inhibitor 5-(N-methyl-N-isobutyl)-amiloride (MIA) for 30 minutes prior to BK stimulation blocked the effect (black diamonds). (B) BK-induced proton efflux was blocked by preincubation with 1 μM of HOE140, a BK B₂ receptor antagonist. The BK B₁ receptor antagonist, des-Arg¹⁰-HOE140, did not change BK-induced ECAR. Experiments were performed three times. Data are mean + SEM.

Abbreviations: BK, bradykinin; ECAR, extracellular acidification rate; NHE, Na⁺/H⁺ exchange; SEM, standard error of the mean.