Rinaldi G, Cingolani H
Centro de Investigaciones Cardiovasculares, La Plata, Argentina.
Can J Cardiol. 1994 Sep;10(7):743-7.
To determine whether vasodilators produce a fall in mean blood pressure (MBP) that is directly proportional to baseline MBP.
The effects on blood pressure of three calcium channel blockers, nitrendipine, nisoldipine and verapamil, were compared with sodium nitroprusside, a drug acting through a different mechanism. The drugs were infused in conscious, unrestrained rats and their effect on MBP was measured.
Primary experimental.
Animals were divided into three groups according to their baseline MBP: high (greater than 119 mmHg), moderate (91 to 119 mmHg) and normal (less than 91 mmHg).
Five successive infusion rates for each drug were tested in each animal. MBP readings were taken at the end of each infusion period (usually 10 mins).
At the maximal dose infused, nitrendipine (0.57 mg/kg.min) lowered MBP 13 +/- 6 mmHg in the low MBP rats, 51 +/- 4 mmHg in the rats with moderate MBP and 83 +/- 8 mmHg in the rats with high MBP (P < 0.05 within groups). Similar results (ie, the greater the baseline MBP, the greater the fall in MBP) were obtained with nisoldipine and verapamil. In the same groups, sodium nitroprusside (0.096 mg/kg.min) produced a fall of 52 +/- 3 mmHg, 56 +/- 5 mmHg and 54 +/- 13 mmHg, respectively (not significant).
Nitrendipine, nisoldipine and verapamil behave as antihypertensives since their effect increased as a function of the initial MBP, while sodium nitroprusside showed no effect related to baseline MBP.
确定血管扩张剂是否会使平均血压（MBP）下降，且下降幅度与基线MBP成正比。
将三种钙通道阻滞剂（尼群地平、尼索地平、维拉帕米）对血压的影响与通过不同机制起作用的硝普钠进行比较。在清醒、不受约束的大鼠中输注这些药物，并测量其对MBP的影响。
主要实验。
根据基线MBP将动物分为三组：高（大于119 mmHg）、中（91至119 mmHg）、正常（小于91 mmHg）。
对每只动物测试每种药物的五个连续输注速率。在每个输注期结束时（通常为10分钟）记录MBP读数。
在最大输注剂量时，尼群地平（0.57 mg/kg·min）使低MBP大鼠的MBP降低13±6 mmHg，中度MBP大鼠降低51±4 mmHg，高MBP大鼠降低83±8 mmHg（组内P<0.05）。尼索地平和维拉帕米也得到了类似结果（即基线MBP越高，MBP下降幅度越大）。在相同组中，硝普钠（0.096 mg/kg·min）分别使MBP下降52±3 mmHg、56±5 mmHg和54±13 mmHg（无显著性差异）。
尼群地平、尼索地平和维拉帕米具有降压作用，因为它们的作用随初始MBP增加而增强，而硝普钠对基线MBP无影响。
