Physiological mechanisms and potentiative effects of pregnancy-induced analgesia by various types of calcium ion channel antagonists at the level of the spinal cord.

这是在大鼠脊髓水平研究妊娠镇痛的生理学和药理学的系列研究之一。(1)We研究L-型钙通道阻滞剂维拉帕米对大鼠脊髓水平妊娠镇痛的影响。采用一次性交配的孕鼠，用甩尾法观察维拉帕米（50 μ g、100 μ g、200 μ g）的镇痛作用。在妊娠动物中，在妊娠后期表现出甩尾潜伏期的显著增加。鞘内注射维拉帕米对晚期妊娠大鼠甩尾潜伏期产生剂量依赖性延长。但在妊娠早期和产后未观察到这种尾板试验的增强作用。结果表明，维拉帕米的协同抗伤害作用，由于与内源性阿片系统的相互作用，只有在怀孕后期激活。（麻醉学1997：87：A653）。（2）本研究旨在评价α 2肾上腺素能激动剂、替扎尼定和可乐定与利多卡因的抗伤害作用和血流动力学的相互作用。使用长期植入腰椎鞘内导管的雄性SD大鼠，使用甩尾试验来评估热伤害性阈值。检测鞘内替扎尼定、可乐定、利多卡因或α-2肾上腺素能激动剂和利多卡因的组合改变甩尾潜伏期的能力。鞘内替扎尼定、可乐定或二者联合给药可增加甩尾潜伏期，呈剂量和时间依赖性，但不影响运动功能。通过等效线分析，替扎尼定和可乐定与利多卡因显示出显著的协同镇痛作用。这些结果可能在临床实践中是有用的，没有循环副作用。（Anesthesiology 1997：87：436-448）。

This is one of series of studies to examine the physiology and pharmacology of pregnancy-induced analgesia at the level of spinal cord in rats.(1)We investigated the effect of L-type calcium channel blocker, verapamil, on pregnancy-induced analgesia at the level of the spinal cord in rats. Using time mated, pregnant rats, antinociceptive effects of verapamil (50mug, 100mug, 200mug) was assessed by tail-flick test. In pregnant animals, a significant increase in tail-flick latency was demonstrated on late in pregnancy. Intrathecally administered verapamil produced a dose-dependent prolongation of tail flick latency on late pregnancy. However, this potensiative effect in tail-flck test was not observed on early gestation and post-partum period. The results suggest a synergistic antinocieptive effect of verapamil due to an interaction with an endogenous opiate system that is only activated late in pregnancy. (Anesthesiology 1997 : 87 : A653).(2)This study was designed to evaluate the anti nociceptive and hemodynamic interactions of alpha-2 adrenergic agonist, tizanidine and clonidine with lidocaine. Using Male SD rats chronically implanted with lumbar intrathecal catheters, the tail-flick test was used to assess the thermal nociceptive threshold. The ability of intrathecal tizanidine, clonidine, lidocaine, or the combinations of alpha-2 adrenergic agonist and lidocaine to alter the tail-flick latency was examined. Intrathccal tizanidine, clonidine, or the combinations increased the tail-flick latency in dose-, and time-dependent fashion without affecting motor function. With isobolographic analysis, tizanidine and clonidine with lidocaine showed significantly synergistic antinociceptive interaction. Theses results may be useful in clinical practice without circulatory side effects. (Anesthesiology 1997 : 87 : 436-448).