Effect of pH on zebrafish GLPs and Aqp1a and human AQP3 expressed in X. laevis oocytes. Oocytes were injected with 1 ng (DrAqp3b, -7, -9a, -9b, -10a, -1a or HsAQP3) or 10 ng (DrAqp3a and -10b) cRNA, or with 50 nl of water (controls). The osmotic water permeability (Pf) was measured in 10 times diluted MBS after 15 min of exposure to isotonic MBS at pH 6, 7.5 or 8.5. The swelling experiments were also performed at the corresponding pH. Data are the means ± SEM of three experiments (n = 10-12 oocytes for each aquaporin). Bars with different superscript in each panel indicate significant differences (ANOVA, p < 0.05) in Pf between aquaporin-injected oocytes. The asterisks denote significant differences with respect the control oocytes at a given pH (Student's t test, p < 0.05).