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

本研究是在大鼠脊髓水平上研究妊娠镇痛的生理和药理学的系列研究之一。(1)从脊髓水平观察l型钙通道阻滞剂维拉帕米对大鼠妊娠镇痛的影响。采用甩尾试验，对不同剂量维拉帕米（50杯、100杯、200杯）的抗伤害感受作用进行了评价。在怀孕的动物中，在怀孕后期，甩尾潜伏期显著增加。鞘内给药维拉帕米在妊娠后期产生了剂量依赖性的甩尾潜伏期延长。然而，在妊娠早期和产后未观察到尾翘试验的潜在影响。结果表明维拉帕米的协同抗避孕作用是由于与内源性阿片系统的相互作用，该系统仅在妊娠后期激活。（麻醉学1997:87:653）。(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性和血流动力学相互作用。用长期植入腰椎鞘内导管的雄性SD大鼠，采用甩尾试验评估热伤害阈值。研究了鞘内注射替扎尼定、柯立定、利多卡因或联合使用α -2肾上腺素能激动剂和利多卡因改变甩尾潜伏期的能力。滴注替扎尼定、可乐定或联合用药以剂量和时间依赖的方式增加甩尾潜伏期，但不影响运动功能。通过等密度分析，替扎尼定和可乐定与利多卡因表现出显著的协同抗感觉相互作用。这些结果可能在临床实践中有用，没有循环副作用。[麻醉学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).