Pörsti I
Department of Biomedical Sciences, University of Tampere, Finland.
J Hypertens. 1992 Mar;10(3):255-63.
To study the effects of a high-calcium diet upon blood pressure, vascular smooth muscle contractions and intracellular free calcium in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats.
Eight-week old animals were placed on a normal-calcium diet (1.1% calcium; SHR and WKY rat groups) or a high-calcium diet (2.1% calcium; Ca-SHR and Ca-WKY rat groups) and observed for 12 weeks.
Blood pressure was measured indirectly by the tail-cuff method and in vitro smooth muscle responses were studied using a standard organ bath chamber. Platelets were used as a cell model for analysis of intracellular free calcium concentration, measured by the fluorescent indicator Quin-2.
The blood pressure of Ca-WKY and WKY rats did not differ, but increased systolic blood pressure was attenuated in Ca-SHR compared with SHR. The concentration-response curves of mesenteric arterial rings for potassium chloride and noradrenaline were not affected by the high-calcium diet in either SHR or WKY rats. The time required for total relaxation after washout of contractile agents (washout time) was shortest in WKY and Ca-WKY rats after both agonists, and shorter in Ca-SHR than in SHR after noradrenaline. Smooth muscle responses were also studied by contracting the preparations with noradrenaline and potassium chloride in a calcium-free solution, after which, calcium was added to the organ bath in increasing concentrations. Calcium contraction responses were similar in WKY and Ca-WKY rats; SHR displayed an attenuated response to calcium addition in mesenteric rings stimulated by both agonists. After potassium chloride as agonist, the responses of SHR and Ca-SHR did not deviate but, after noradrenaline, a significant shift in the calcium contraction curve towards the normotensive curve was observed in Ca-SHR. Intracellular free calcium was clearly lower in WKY rats than in SHR, and was significantly reduced by calcium supplementation in the hypertensive but not the normotensive animals.
A reduction in intracellular free calcium concentration and an effect upon receptor-mediated vascular smooth muscle contraction and excitation-contraction coupling may participate in the blood pressure lowering effect of a high-calcium diet.
研究高钙饮食对自发性高血压大鼠（SHR）和正常血压的Wistar-Kyoto（WKY）大鼠血压、血管平滑肌收缩及细胞内游离钙的影响。
将8周龄动物分为正常钙饮食组（钙含量1.1%；SHR和WKY大鼠组）或高钙饮食组（钙含量2.1%；Ca-SHR和Ca-WKY大鼠组），观察12周。
采用尾套法间接测量血压，使用标准器官浴槽研究体外平滑肌反应。以血小板作为细胞模型，用荧光指示剂喹啉-2测量细胞内游离钙浓度。
Ca-WKY大鼠和WKY大鼠的血压无差异，但与SHR相比，Ca-SHR大鼠收缩压升高有所减弱。氯化钾和去甲肾上腺素引起的肠系膜动脉环浓度-反应曲线在SHR和WKY大鼠中均不受高钙饮食影响。两种激动剂作用后，WKY和Ca-WKY大鼠洗脱收缩剂后的总舒张时间最短，去甲肾上腺素作用后Ca-SHR大鼠的总舒张时间比SHR大鼠短。在无钙溶液中用去甲肾上腺素和氯化钾收缩标本后，再向器官浴槽中加入浓度递增的钙，以此研究平滑肌反应。WKY和Ca-WKY大鼠的钙收缩反应相似；在两种激动剂刺激的肠系膜环中，SHR对钙添加的反应减弱。以氯化钾作为激动剂时，SHR和Ca-SHR的反应无偏差，但以去甲肾上腺素作为激动剂时，Ca-SHR的钙收缩曲线明显向正常血压曲线偏移。WKY大鼠细胞内游离钙明显低于SHR，补充钙可使高血压动物而非正常血压动物的细胞内游离钙显著降低。
细胞内游离钙浓度降低以及对受体介导的血管平滑肌收缩和兴奋-收缩偶联的影响可能参与了高钙饮食的降压作用。
