Kao H W, Hyman P E, Finn S E, Snape W J
Department of Medicine, Harbor-UCLA Medical Center, Torrance 90509.
Am J Physiol. 1988 Dec;255(6 Pt 1):G807-12. doi: 10.1152/ajpgi.1988.255.6.G807.
Isolated circular smooth muscle cells from the rabbit distal colon were used to study the effect of prostaglandin E2 (PGE2) on bethanechol-stimulated smooth muscle cell contraction. Contraction was expressed as the percentage decrease in mean cell length compared with unstimulated cells. Incubation with different concentrations of PGE2 (10(-10)-10(-6) M) did not cause contraction or relaxation of unstimulated smooth muscle cells. Bethanechol stimulated a dose-dependent contraction that was maximal at 30 s. The threshold for bethanechol-stimulated contraction was 10(-11) M; the ED50 was 10(-10) M; and the maximum contraction (23.0 +/- 1.8%) occurred at 10(-8) M. Preincubation with PGE2 reduced both the efficacy and potency of bethanechol-stimulated contraction. Preincubation with 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or dibutyryl-cAMP reduced the efficacy of bethanechol-stimulated contraction without affecting potency. Increasing concentrations of PGE2 stimulated a dose-dependent increase in the production of intracellular cAMP (P less than 0.05). These studies show that PGE2 inhibits bethanechol-stimulated contraction of isolated colonic circular myocytes and is associated with increased production of intracellular cAMP. There is also a cAMP-independent effect of PGE2 on the potency of bethanechol stimulation.
采用兔远端结肠分离出的环形平滑肌细胞，研究前列腺素E2（PGE2）对氨甲酰甲胆碱刺激的平滑肌细胞收缩的影响。收缩程度以与未受刺激细胞相比平均细胞长度的减少百分比表示。用不同浓度的PGE2（10^(-10)-10^(-6) M）孵育未受刺激的平滑肌细胞，未引起收缩或舒张。氨甲酰甲胆碱刺激产生剂量依赖性收缩，30 s时达到最大。氨甲酰甲胆碱刺激收缩的阈值为10^(-11) M；半数有效剂量（ED50）为10^(-10) M；在10^(-8) M时出现最大收缩（23.0±1.8%）。PGE2预孵育降低了氨甲酰甲胆碱刺激收缩的效能和效价。8-溴腺苷3',5'-环磷酸（8-BrcAMP）或二丁酰环磷腺苷（dibutyryl-cAMP）预孵育降低了氨甲酰甲胆碱刺激收缩的效能，但不影响效价。PGE2浓度增加刺激细胞内cAMP生成呈剂量依赖性增加（P<0.05）。这些研究表明，PGE2抑制氨甲酰甲胆碱刺激的离体结肠环形肌细胞收缩，并与细胞内cAMP生成增加有关。PGE2对氨甲酰甲胆碱刺激效价也有不依赖cAMP的作用。
