Kousides M, Story M E, Pennefather J N, Ziccone S P, Ross A W
Department of Pharmacology, Monash University, Clayton, Vic. Australia.
Reprod Fertil Dev. 1995;7(1):59-66. doi: 10.1071/rd9950059.
The hypothesis that inhibitory effects of isoprenaline on myometrial contractility may be constrained by activation of putative intracellular beta-adrenoceptors negatively-coupled to adenylate cyclase was examined. Field-stimulated preparations of guinea-pig and human myometrium were used to examine the influence of the catecholamine extraneuronal uptake2 inhibitors, corticosterone and beta-oestradiol, on the inhibitory effects of the beta-adrenoceptor agonist, isoprenaline, on uterine contraction. Longitudinal and circular myometrial layers were obtained from guinea-pigs in dioestrus, primed with oestrogen before progesterone, or pregnant (Days 62-65). In the guinea-pig myometrium, corticosterone (30 microM) did not affect responses to isoprenaline. beta-oestradiol (10 microM) induced a small potentiation of the effects of isoprenaline on longitudinal myometrium from dioestrus guinea-pigs. Myometrial preparations were obtained from pregnant women (36-40 weeks gestation) undergoing caesarean section. Isoprenaline inhibited stimulation-evoked contractions in 7 of 10 preparations of the inner myometrial layer and in 5 of 8 preparations of outer myometrial layer. Corticosterone (30 microM) reduced the effects of isoprenaline on the inner layer and did not affect the outer layer. These results do not support the existence of mechanism involving isoprenaline-sensitive intracellular receptors which constrain responses to beta-adrenoceptor agonists.
研究了异丙肾上腺素对子宫肌层收缩性的抑制作用可能受假定的与腺苷酸环化酶负偶联的细胞内β-肾上腺素能受体激活的限制这一假说。使用豚鼠和人子宫肌层的场刺激制备物来研究儿茶酚胺非神经元摄取2抑制剂、皮质酮和β-雌二醇对β-肾上腺素能受体激动剂异丙肾上腺素对子宫收缩抑制作用的影响。从处于动情间期的豚鼠、在孕酮之前用雌激素预处理的豚鼠或怀孕（第62 - 65天）的豚鼠中获取子宫肌层的纵行和环行层。在豚鼠子宫肌层中，皮质酮（30微摩尔）不影响对异丙肾上腺素的反应。β-雌二醇（10微摩尔）使异丙肾上腺素对动情间期豚鼠纵行子宫肌层的作用有小幅度增强。从行剖宫产的孕妇（妊娠36 - 40周）获取子宫肌层制备物。异丙肾上腺素抑制了10份子宫肌层内层制备物中的7份以及8份子宫肌层外层制备物中的5份的刺激诱发收缩。皮质酮（30微摩尔）减弱了异丙肾上腺素对内层的作用，对外层无影响。这些结果不支持存在涉及异丙肾上腺素敏感的细胞内受体从而限制对β-肾上腺素能受体激动剂反应的机制。
