Figure 4.

Effects of dietary sugars on intestinal P_i absorption in lactating and virgin rats. Transepithelial P_i transport was measured using everted intestinal sacs from the proximal jejunum of lactating and virgin rats fed a glucose (G), fructose (F), or starch (S) diet for ∼6 wk. A) Active Na⁺-dependent transepithelial P_i transport from the luminal to the basolateral compartments was calculated as the total transepithelial P_i transport subtracted by Na⁺-independent P_i transport. Because of the low rates of active P_i transport in adult rats (44), which fluctuated around 0, we could not express rates relative to virgin rats. B) NaPi2b mRNA expression was analyzed by real-time PCR using EF1α as a reference. Bars, analyses, and normalization as in Fig. 1.