Expression of renal AQP2. Renal expression of AQP2 protein and mRNA in kidneys from rats fed a control and low-protein diet during pregnancy (A & C) and in non-pregnant rats at different stages of the oestrus cycle (B & D). Data is presented as mean ± SEM (n = 6-8 per group). Data was analysed by one or two-way ANOVA as described in the methods section. Representative western blots are shown. There was a significant interaction between gestational age and diet in their effects on AQP2 mRNA (P < 0.05) and protein (P < 0.05). Different superscripts show the effects of gestational age on AQP2 expression (b > a, P < 0.05).