Normal mice are shown in black lines and squares. Mice not expressing ET-1 in the collecting duct (CD ET-1 KO) are shown in dashed lines and open circles. Normal mice exhibit transient Na+ retention before escaping from progressive positive Na+ balance. CD ET-1 KO fail to undergo aldosterone escape, with persistent positive daily Na+ balance. Daily Na+ balance over days 1–19. Solid lines are controls, and dotted lines are CD ET-1 KO. Control, n = 9; CD ET-1 KO, n = 6. Data is shown as means + SE. In B, *P < 0.05 within control, day 1 vs. days 2, 3, 6, and 7, Tukey's test; †P < 0.05 within control, day 11 vs. days 9–12 and 14–19, Tukey's test; ‡P < 0.05, significant effect of genotype, repeated-measures ANOVA. Adapted from Lynch et al (506).