Figure 2.

Growth and serum chemistries of the VDR ablated mice. (A) Male mice of all three genotypes were weighed at weekly intervals from 2 to 13 weeks of age. The wild-type (squares) and heterozygous (circles) mice grow at a similar rate; however, the homozygous ablated (diamonds) mice gain weight more slowly after weaning (at 21 days of age). All values are based on three to five animals, and errors represent the SEM. Absence of error bars indicates points where the SEM is less than 0.6. The shape of the female weight curve is similar. (B) Ionized calcium measurements (in mmol/L, corrected for pH) were performed at weekly intervals from 2 to 13 weeks of age. Day 14 samples were obtained by cardiac puncture under isoflurane anesthesia. All other samples were obtained by tail nicking. The wild-type (squares) and heterozygous (circles) mice have similar levels, whereas the homozygous mice (diamonds) become hypocalcemic after weaning. All values represent the mean and SEM based on measurements in three to five animals. Absence of error bars indicates points where the SEM is less than 0.01. There was no sex difference in ionized calcium values. (C) Immunoreactive PTH values were measured using a rat PTH assay. iPTH values in the wild-type (squares) and heterozygous mice (data not shown) were less than 18 pg/ml at all stages. iPTH levels in the vitamin D receptor ablated mice (diamonds) were indistinguishable from those of their heterozygous and wild-type littermates at 15 and 19 days of age but by 21 days began to rise. All values are based on the mean and SEM of sera from three mice of the same genotype.