Table 2.
Effect of Low Calcium Diet on Skeletal Characteristics of WT and β-Arrestin2−/− Mice
|
WT |
β-arrestin2−/− |
|||
| Control (n = 9) | Low Ca (n = 8) | Control (n = 8) | Low Ca (n = 9)* | |
| BMD change (%) | ||||
| Total body | 4.0 ± 1.4 | −3.3 ± 1.2† | 2.7 ± 0.8 | −6.0 ± 1.1† |
| Lumbar spine | −2.1 ± 3.3 | −23.3 ± 4.9† | −2.9 ± 3.0 | −24.9 ± 3.3† |
| Femoral shaft | 3.8 ± 1.6 | −4.8 ± 2.7‡ | 2.9 ± 1.2 | −3.2 ± 1.2† |
| Vertebral trabecular bone | ||||
| BV/TV (%) | 30.3 ± 0.9 | 26.0 ± 1.3‡ | 29.4 ± 0.9 | 23.9 ± 1.3§ |
| TbTh (μm) | 56.2 ± 1.7 | 55.8 ± 2.2 | 58.1 ± 1.7 | 53.6 ± 1.7 |
| TbN (mm−1) | 5.30 ± 0.08 | 4.97 ± 0.14 | 4.96 ± 0.10¶ | 4.47 ± 0.13‡¶ |
| TbSp (μm) | 175 ± 3 | 190 ± 7 | 188 ± 5¶ | 214 ± 8‡¶ |
| Distal femur trabecular bone | ||||
| BV/TV (%) | 19.7 ± 1.1 | 14.3 ± 1.0† | 18.7 ± 1.2 | 14.2 ± 1.5‡ |
| TbTh (μm) | 56.4 ± 1.7 | 57.5 ± 2.7 | 58.4 ± 1.5 | 56.2 ± 2.0 |
| TbN (mm−1) | 4.70 ± 0.09 | 3.99 ± 0.11† | 4.20 ± 0.08¶ | 3.78 ± 0.08† |
| TbSp (μm) | 200 ± 6 | 243 ± 9† | 228 ± 5¶ | 256 ± 6† |
| Cortical bone (diaphysis) | ||||
| Total area (mm2) | 2.13 ± 0.07 | 2.03 ± 0.08 | 2.07 ± 0.08 | 1.98 ± 0.07 |
| Bone area (mm2) | 0.92 ± 0.05 | 0.85 ± 0.03 | 0.93 ± 0.04 | 0.80 ± 0.04‡ |
| Medullary area (mm2) | 1.22 ± 0.04 | 1.18 ± 0.06 | 1.14 ± 0.05 | 1.18 ± 0.04 |
| BA/TA (%) | 42.8 ± 1.5 | 42.1 ± 1.1 | 45.1 ± 0.5 | 40.5 ± 0.7† |
| Cortical thickness (μm) | 181 ± 7 | 178 ± 4 | 196 ± 4 | 170 ± 4‡ |
* n = 7 for β-arrestin2−/− vertebral specimens.
† p < 0.005, ‡ p < 0.05, and § p < 0.01 vs. control diet within genotype.
¶ p < 0.05 vs. WT within diet group.
BV/TV, bone volume fraction; TbTh, trabecular thickness; TbN, trabecular number; TbSp, trabecular separation; BA/TA, bone area fraction.