Fig. 6.

Decreased Per1 results in impaired renal Na⁺ conservation. Weight-matched male WT 129/sv and Per1 het mice were placed in metabolic cages and allowed to acclimate for 3 days. Per1 het mice were fed the same amount of food as the WT mice ate the previous day. Mice were fed a normal gel diet (0.2% Na⁺) with free access to water. After 3 days, mice were switched to a low-Na⁺ diet (0.02%) for 7 days. Urine samples were collected daily. Flame photometry was performed to determine urinary Na⁺ concentrations. A: urinary Na⁺ retention over time with the average urinary Na⁺ retention during the normal diet and low-Na⁺ diet. n = 5. *P < 0.05 compared with WT mice on given day. B: data shown by genotype and diet, averaged over the course of the normal diet (days 1–3) versus the low-Na⁺ diet (days 4–10). n = 5. *P < 0.05 compared with WT mice; †P < 0.05 compared with time (noon vs. midnight); ‡P < 0.01, significant interaction by two-way ANOVA. C: body weight relative to starting weight (day 3 of the acclimation period). n = 5. *P < 0.05 compared with control.