补钙可减弱犬缺氧性肺血管收缩反应

Pulmonary Vascular Constrictive Response to Hypoxia Could Be Depressed by Calcium Supplement

研究补充钙对缺氧性肺血管收缩反应及脑血管舒张反应的影响。在全麻狗，静脉滴注ＣａＣｌ２生理盐水（１ｍｇ·ｋｇ－１·ｍｉｎ－１）。用原子吸收光谱法测定血清钙，输钙前后分别测常氧与缺氧时血流动力学指标，并测右颈总动脉血流量反映相对脑血流量（ＣＢＦ）。以缺氧时肺血管阻力（ＰＶＲ）和ＣＢＦ变化率（ｄＰＶＲ％，ｄＣＢＦ％）反映血管反应强度。结果：常氧下血清钙从１．６５～１．８５ｍｍｏｌ／Ｌ增加至３．１０～３．２０ｍｍｏｌ／Ｌ时可降低平均肺动脉压（ｍＰＡＰ）（Ｐ＜０．０１），此时平均体动脉压、体血管阻力、心输出量（ＣＯ）和ＣＢＦ均无明显变化。补钙前吸１０％氧５ｍｉｎ时ｍＰＡＰ、ＰＶＲ、ＣＢＦ、ＣＯ都增加（均为Ｐ＜０．０１）。补钙后缺氧５ｍｉｎ，ｍＰＡＰ、ＰＶＲ增高程度和ｄＰＶＲ％均较未用钙时小（Ｐ分别为＜０．０５、＜０．０１、＜０．０１），ＣＢＦ的变化无显著性意义。提示补一定浓度钙可减轻缺氧性肺动脉高压而无增强缺氧性脑血管舒张反应的副作用。

To investigate the effect of calcium supplement on the hypoxic responsiveness of pulmonary and cerebral vessels, anesthetized dogs were given CaCl2 saline(1mgkg-1 min-1) intravenously The serum calcium levels were measured by atomic absorption spectroscopy method The haemodynamic parameters were determined The vascular responsiveness was expressed by the percentage of the hypoxic changes in pulmonary vascular resistance and cerebral blood flow(dPVR%,dCBF%) The results showed that the mean pulmonary artery pressure(mPAP) was decreased in normoxia when the concentration of serum calcium increased from 165185 mmol/L up to 310320 mmol/L (P<001), whereas the mean systemic artery pressure, systemic artery resistance, cardiac output(CO) and CBF remained unchanged mPAP,pulmonary vascular resistance(PVR),CBF and CO were increased during the inspiration of 10%O2 for 5 min (P<001) The increase in mPAP and PVR in hypoxic dogs with hypercalcemia were not as significant as those before calcium supplement (P<005 and <001, respectively). However, there was no statistic significance in the hypoxic change of CBF between groups before and after calcium administration It is suggested that calcium administration might reduce hypoxic pulmonary hypertension without the side effect of enhancing cerebral vascular dilatation