Nesheim B I, Sigurdsson S B
Acta Pharmacol Toxicol (Copenh). 1978 May;42(5):371-6. doi: 10.1111/j.1600-0773.1978.tb02219.x.
Mechanical and electrical responses of spontaneously contracting muscle strips from oestrogen dominated rabbit uterus were investigated by the sucrose gap method. The effects of isoprenaline and dibutyryl-c-AMP in the presence and absence of propranolol were tested. It has been shown previously that the beta-adrenoceptor agonist isoprenaline inhibits the spontaneously contracting uterus even in the presence of the beta-blocker propranolol. The rise in c-amp which is caused by isoprenaline, is, however, blocked by propranolol. The aim of this investigation was to study further the role of c-AMP in the isoprenaline-induced relaxation of the uterus. Isoprenaline (10(-6) M) consistently abolished spikes and mechanical contractions, usually accompanied by hyperpolarization. Propranolol (3 X 10(-6) M) markedly reduced the incidence of hyperpolarization, but did not affect the other actions of isoprenaline. Hyperpolarization does not seem to be a prerequisite for inhibition of uterine contraction. Dibutyryl-c-AMP mimicked the actions of isoprenaline. No positive evidence to support a hypothesis of a c-AMP-independent mechanism was found. Therefore a possible explanation of the results could be that isoprenaline increases c-AMP in a small intracellular pool, mediating electrical and mechanical responses but not influenced by propranolol.
采用蔗糖间隙法研究了雌激素占主导的兔子宫自发收缩肌条的机电反应。测试了在有无普萘洛尔存在的情况下异丙肾上腺素和二丁酰环磷腺苷（dibutyryl-c-AMP）的作用。先前已表明，即使在存在β受体阻滞剂普萘洛尔的情况下，β肾上腺素能受体激动剂异丙肾上腺素也会抑制子宫的自发收缩。然而，由异丙肾上腺素引起的环磷腺苷（c-AMP）升高会被普萘洛尔阻断。本研究的目的是进一步研究环磷腺苷在异丙肾上腺素诱导的子宫松弛中的作用。异丙肾上腺素（10⁻⁶ M）始终消除尖峰和机械收缩，通常伴有超极化。普萘洛尔（3×10⁻⁶ M）显著降低超极化的发生率，但不影响异丙肾上腺素的其他作用。超极化似乎不是抑制子宫收缩的先决条件。二丁酰环磷腺苷模仿了异丙肾上腺素的作用。未发现支持环磷腺苷非依赖性机制假说的阳性证据。因此，对结果的一种可能解释是，异丙肾上腺素增加了细胞内一个小池中的环磷腺苷，介导电和机械反应，但不受普萘洛尔影响。
