Figure 10.

Changes in rates of intestinal Ca²⁺ transport varied with levels of 1,25-(OH)₂D₃ and abundance of 1α-hydroxylase. A) Variations in mean enterocyte Ca²⁺ accumulation are strongly correlated with average concentrations of 1,25-(OH)₂D₃ in rats. B) Average circulating levels of 1,25-(OH)₂D₃ are tightly correlated with mean relative mRNA expression levels of CYP27B1. C) Relative expression of CYP27B1 mRNA is independent of PTH levels. Regression coefficients and significance (P) are in boxes.