Figure 7.
Effect of the CHP1-NHE3 complex formation on NHE3 acute regulation by specific hormonal stimuli. A, B) Effect of dopamine (10−5 M, 10 min) on NHE3 H+ flux with (A, right panel) and without (A, left panel) perfusion with the NHE3478–500-WT peptide at pHi 6.5; and on NHE3 H+ flux at pHi 6.0 and 6.5 (B, first and second bars) and on NHE3 H+ flux at pH 6.5, before and after perfusion with the NHE3478–500-WT peptide (B, second and third bars). Results are a percentage of the control of NHE3 activity. Data in the first and second bars were normalized by comparing dopamine 10−5 M-treated with vehicle-treated cells at pH 6.0 and 6.5. Data presented in the third bar were dopamine 10−5 M and peptide perfusion compared with vehicle and peptide perfusion. C) Effect of 8-Br-cAMP (10−4 M, 10 min) on NHE3 H+ flux, before and after perfusion with the NHE3478–500-WT peptide at pHi 6.5. Data were normalized as in B. D) Effect of CPA (10−6 M, 10 min), on NHE3 H+ flux at pHi 6.0 and 6.5 and reverse of CPA-mediated inhibition of NHE3 H+ flux at pHi 6.5 by perfusion with NHE3478–500-WT peptide. Data were normalized as in B. Results are presented as a percentage of the control of NHE3 activity. Circles, bars, and error bars: means ± se. Numbers in parentheses: experiments performed in identical conditions. *P < 0.05, **P < 0.01 vs. control; ANOVA. $P < 0.05; ANOVA. ▲P < 0.05; ANOVA.