Cirillo M, Galletti F, Corrado M F, Strazzullo P
J Hypertens. 1986 Aug;4(4):443-9. doi: 10.1097/00004872-198608000-00008.
Urinary calcium (Ca) excretion and erythrocyte membrane Ca binding and transport were investigated in rats of the Milan hypertensive (MHS) and normotensive strains (MNS). Despite slightly reduced ionized Ca levels in the serum, MHS significantly increased urinary Ca excretion under fasting conditions (P less than 0.01). Urinary Ca was positively related to sodium (Na) excretion in both rat strains; moreover the urinary Ca:Na ratio was significantly enhanced in MHS rats (P less than 0.05). These data suggest that in MHS, Ca reabsorption in the renal tubular cell is reduced independently of disturbances in Na handling. Adenosine triphosphate (ATP)-dependent Ca transport, reflecting the Ca, magnesium (Mg)-ATPase activity (Ca pump), was measured in inside-out vesicles obtained from erythrocyte membranes. This variable was significantly reduced in MHS (P less than 0.01), with no change in the Ca pump affinity constant for Ca. Calcium binding to erythrocyte membranes, measured in the presence of free Ca concentrations comparable with those of the intracellular fluid, was found to be significantly reduced (P less than 0.01) in MHS rats because of the lower number of Ca binding sites. These abnormalities of red blood cell (RBC) Ca handling are in keeping with the increased Ca clearance observed in the kidney. It is not clear whether the disturbances of renal and erythrocyte Ca handling were a genetic primary defect or a secondary change of membrane function.
对米兰高血压大鼠（MHS）和正常血压大鼠（MNS）的尿钙（Ca）排泄以及红细胞膜钙结合与转运进行了研究。尽管血清中离子钙水平略有降低，但MHS大鼠在禁食条件下尿钙排泄显著增加（P<0.01）。两种大鼠品系中尿钙均与钠（Na）排泄呈正相关；此外，MHS大鼠的尿钙：钠比值显著升高（P<0.05）。这些数据表明，在MHS大鼠中，肾小管细胞的钙重吸收减少，且与钠处理紊乱无关。在从红细胞膜获得的内翻囊泡中测量了反映钙、镁（Mg）-ATP酶活性（钙泵）的三磷酸腺苷（ATP）依赖性钙转运。该变量在MHS大鼠中显著降低（P<0.01），而钙泵对钙的亲和力常数无变化。在与细胞内液相当的游离钙浓度存在下测量的红细胞膜钙结合，发现MHS大鼠中由于钙结合位点数量减少而显著降低（P<0.01）。红细胞（RBC）钙处理的这些异常与肾脏中观察到的钙清除增加一致。目前尚不清楚肾脏和红细胞钙处理的紊乱是遗传原发性缺陷还是膜功能的继发性改变。
