Segal S, Csavoy A N, Datta S
Department of Anesthesia Research Laboratories, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Anesth Analg. 1998 Oct;87(4):864-9. doi: 10.1097/00000539-199810000-00022.
Maternal catecholamines increase dramatically in labor because of pain and emotional stress. Because the uterus is richly endowed with both alpha- and beta-adrenergic receptors, catecholamines could alter uterine activity. We assessed the effect of clinically encountered concentrations of these catecholamines on uterine activity and modeled the effect of the abrupt reduction in circulating epinephrine that occurs during effective labor analgesia. Term pregnant rat uteri were excised, and cross-sectional rings were mounted for isometric force recording. Log concentration-response curves for epinephrine, norepinephrine, and their combination on uterine activity were constructed from 10(-12) to 10(-6) M. Catecholamine responses were repeated in the presence of phentolamine, an alpha-adrenergic blocker or propranolol, a beta-adrenergic blocker. The abilities of oxytocin and of washout of catecholamines to reverse catecholamine-induced changes in uterine activity were also assessed. Epinephrine caused dose-dependent reductions in uterine activity, blocked by propranolol. Epinephrine concentrations in the clinical range(10(-9) to 10(-8) M; 100-1000 pg/mL) decreased uterine activity to 49.6% +/- 6.6% (mean +/- SE) of control. Norepinephrine caused a dose-dependent increase in uterine activity, which was blocked by phentolamine. In the clinical range (10(-8) M), uterine activity was 139.2% +/- 13.40% of control. The combination of both catecholamines, however, was nearly as tocolytic as epinephrine alone. Oxytocin antagonized catecholamine-induced tocolysis, and washout of epinephrine or both catecholamines increased uterine activity. We conclude that mixed catecholamines are significantly tocolytic at concentrations encountered in laboring women. In this in vitro model, reduction in epinephrine concentration, comparable to that which occurs during effective analgesia, significantly increases uterine activity.
Maternal catecholamines increase in labor, but epinephrine decreases dramatically after regional analgesia. In this study, we found that norepinephrine and epinephrine together decrease uterine contractile activity and that decreased epinephrine causes significantly increased uterine activity.
由于疼痛和情绪压力，产妇在分娩时儿茶酚胺会急剧增加。由于子宫富含α和β肾上腺素能受体，儿茶酚胺可能会改变子宫活动。我们评估了临床中遇到的这些儿茶酚胺浓度对子宫活动的影响，并模拟了有效分娩镇痛期间循环肾上腺素突然减少的影响。切除足月妊娠大鼠的子宫，制备横截面环用于等长力记录。构建肾上腺素、去甲肾上腺素及其组合对子宫活动的对数浓度-反应曲线，浓度范围为10(-12)至10(-6)M。在α肾上腺素能阻滞剂酚妥拉明或β肾上腺素能阻滞剂普萘洛尔存在的情况下重复儿茶酚胺反应。还评估了催产素以及儿茶酚胺洗脱逆转儿茶酚胺诱导的子宫活动变化的能力。肾上腺素导致子宫活动呈剂量依赖性降低，普萘洛尔可阻断这种作用。临床范围内的肾上腺素浓度（10(-9)至10(-8)M；100 - 1000 pg/mL）使子宫活动降至对照的49.6%±6.6%（平均值±标准误）。去甲肾上腺素导致子宫活动呈剂量依赖性增加，酚妥拉明可阻断这种作用。在临床范围内（10(-8)M），子宫活动为对照的139.2%±13.40%。然而，两种儿茶酚胺的组合几乎与单独使用肾上腺素一样具有宫缩抑制作用。催产素可拮抗儿茶酚胺诱导的宫缩抑制作用，肾上腺素或两种儿茶酚胺的洗脱均可增加子宫活动。我们得出结论，混合儿茶酚胺在分娩妇女体内遇到的浓度下具有显著的宫缩抑制作用。在这个体外模型中，与有效镇痛期间发生的情况相当的肾上腺素浓度降低会显著增加子宫活动。
产妇在分娩时儿茶酚胺增加，但区域镇痛后肾上腺素会急剧下降。在本研究中，我们发现去甲肾上腺素和肾上腺素共同降低子宫收缩活动，而肾上腺素减少会导致子宫活动显著增加。
