McCarron D A, Yung N N, Ugoretz B A, Krutzik S
Hypertension. 1981 May-Jun;3(3 Pt 2):I162-7. doi: 10.1161/01.hyp.3.3_pt_2.i162.
Ionized calcium is critical to the maintenance of normal cardiovascular function. Recently, vasoactive properties have also been attributed to parathyroid hormone (PTH). The present study characterizes the calcium-PTH axis in the spontaneously hypertensive rat (SHR) in order to determine the effects of chronic alterations in calcium intake on the development and maintenance of hypertension in this species. Thirty-six SHR and 36 Wistar-Kyoto (WKY) normotensive control rats were studied. The rats were fed one of three levels (percent of total diet) of calcium (normal 0.5%, low-normal 0.25%, high 4.0%) beginning at 10 weeks of age. Serum total and ionized calcium, serum PTHs, urinary electrolytes, and systolic blood pressures were assessed by repeated measurements between 10 and 48 weeks of age. Irrespective of calcium intake, the SHRs had lower serum ionized calcium concentrations (p less than 0.001) and higher PTH levels (p less than 0.001) than the WKYs. Serum total calcium were similar for the two strains. Urinary calcium excretion was greater in the SHR (p less than 0.001) relative to the WKY. The high (4.0%) calcium diet normalized the serum ionized calcium and attenuated the development of the SHRs' hypertension (p less than 0.001). The present study describes several previously unrecognized abnormalities of calcium metabolism in the SHR. These disturbances may be of pathogenetic importance in the development and maintenance of hypertension in the SHR.
离子钙对于维持正常心血管功能至关重要。最近，血管活性特性也被归因于甲状旁腺激素（PTH）。本研究对自发性高血压大鼠（SHR）的钙 - PTH轴进行了表征，以确定钙摄入量的长期改变对该物种高血压发生和维持的影响。研究了36只SHR和36只Wistar - Kyoto（WKY）正常血压对照大鼠。从10周龄开始，给大鼠喂食三种钙水平（占总饮食的百分比）之一（正常0.5%、低正常0.25%、高4.0%）。在10至48周龄期间通过重复测量评估血清总钙和离子钙、血清PTH、尿电解质和收缩压。无论钙摄入量如何，SHR的血清离子钙浓度均低于WKY（p < 0.001），PTH水平高于WKY（p < 0.001）。两种品系的血清总钙相似。相对于WKY，SHR的尿钙排泄量更大（p < 0.001）。高钙（4.0%）饮食使血清离子钙正常化，并减轻了SHR高血压的发展（p < 0.001）。本研究描述了SHR中几种先前未被认识到的钙代谢异常。这些紊乱可能在SHR高血压的发生和维持中具有致病重要性。
