The effect of hypertension on bone decrease in hypertensive rats

1. 高盐摄取量对大鼠下颌骨的影响将28只11周龄雄性DS大鼠分为4组。对照组饲喂正常（0.2% NaCl）饲粮，试验组饲喂添加8.0% NaCl的饲粮。与对照组相比，实验组的收缩压明显升高。实验第8周或第22周，以乙醚麻醉处死动物。血浆和尿液生化数据显示实验组与对照组相比存在负钙平衡。高盐负荷第22周骨矿物质密度显著降低。组织形态学分析提示，高盐负荷第8周时下颌骨体积减小已经开始，骨吸收增加，骨形成减少，高盐负荷第22周时骨重塑失衡恢复正常。总之，这些结果表明，高盐摄入不仅会导致严重的高血压，还会导致DS大鼠的下颌骨减少。高血压对自发性高血压大鼠（SHR）骨密度的影响与正常遗传对照Wistar Kyoto大鼠（WKY）相比，SHR的收缩压明显升高。7周龄SHR与WKY的胫骨、下颌骨骨密度无显著差异。然而，34周龄SHR的胫骨骨密度明显低于34周龄WKY。皮质骨差异无统计学意义，松质骨差异有统计学意义。这些结果表明，高血压可能不会显著降低下颌骨的总矿物质密度，因为下颌骨的松质骨比胫骨少。

1. The effect of high salt intake on the mandibular bone in Dahl-Iwai salt-sensitive (DS) ratsTwenty-eight 11-week-old male DS rats were divided into four groups. The control groups received a normal (0.2% NaCl) diet while the experimental groups received a diet supplemented with 8.0% NaCl. The systolic blood pressure was significantly increased in the experimental groups compared to the control groups. The animals were sacrificed under ether anesthesia at the 8th week or the 22nd week of the experiment. The biochemical data in plasma and urine suggested negative calcium balance in the experimental groups compared to the control groups. The bone mineral density was significantly reduced at the 22nd week of high salt loading. The histomorphometric analysis suggested that the reduction of the mandibular bone volume had already started by the 8th week of high salt loading along with the increased bone resorption and the decreased bone formation, and that the improper bone remodeling balance became normalized by the 22nd week of high salt loading. In conclusion, these results indicate that a high salt intake causes not only severe hypertension but also a mandibular bone reduction in the DS rats.2. The effect of hypertension on bone mineral density in spontaneously hypertensive rats (SHR)The systolic-blood pressure was significantly increased in SHR compared to their normotensive genetic control Wistar Kyoto rats (WKY). There was no difference in bone mineral density of tibia and mandible between 7-week-old SHR and WKY.However, bone mineral density of tibia was significantly lower in 34-week-old SHR than in 34-week-old WKY.There was no difference in cortical bone but significant difference in cancellous bone. These results indicate that hypertension may not significantly reduce total mineral density of mandible because there is smaller amount of cancellous bone in mandible than in tibia.