No Effect of Short-Term Hypertension on Bone Matrix Mineralization in a Surgical Animal Model in Immature Rabbits

Epidemiological studies show that arterial hypertension is associated with bone loss and an increased risk of fractures. Bone material properties are essential for bone strength. However, little is known about the effects of hypertension on bone matrix mineralization. Genetic animal models of hypertension are not ideal for studying bone matrix properties since these mutations may affect mineralization per se. The purpose of this study was to evaluate the effects of short-term hypertension on bone mineral density distribution (BMDD) using quantitative backscattered electron imaging in the proximal humerus in an established surgical model of pressure-overload cardiac hypertrophy in immature rabbits. Banding of the descending aorta was performed in 10-day-old rabbits (n = 4). Systolic blood pressure was elevated at all timepoints in the upper extremity but reached statistical significance at 5 and 6 weeks of age (+30.1% and +25.1 mm Hg; P < 0.05 each, respectively). Diastolic blood pressure was not affected. The left proximal humerus was harvested at 6 weeks of age, which is the maximum time in this animal model. Four non-operated, matched animals served as controls. Bone mineral density distribution parameters were determined in the epiphyseal and metaphyseal regions of the proximal humerus. The bone mineral density distribution parameters which describe the degree and heterogeneity of mineralization as well as the amount of low mineralized matrix showed no significant differences. Moreover no difference in bone length was found. Our study indicates that short-term elevation of blood pressure has no effects on bone matrix mineralization in this surgical model of pressure-overload cardiac hypertrophy in immature rabbits.