Tuross N, Mahtani M, Marshall J M
Section of Neurobiology, Brown University, Providence, Rhode Island 02912.
Biol Reprod. 1987 Sep;37(2):348-55. doi: 10.1095/biolreprod37.2.348.
Previous studies showed that circular (CM) and longitudinal myometrium (LM) have different physiological and pharmacological characteristics. To determine if such differences also exist with respect to the actions of oxytocin and prostaglandin F2-alpha (PGF2 alpha), we compared the effects of these agents on the spontaneous contractions of CM and LM from rats on Days 15, 17, and 21 (term) of pregnancy. Both agents stimulated CM and LM on all gestation days, but the responses differed as follows: 1) the CM response to oxytocin was all-or-nothing on Days 15 and 17, to PGF2 alpha on Day 15, and was graded to both agents only at term; 2) the LM response to both agents was always graded; 3) the maximum response to oxytocin was always less in CM than in LM, and to PGF2 alpha was less in CM except at term, when it was greater than in LM; 4) the EC50 (effective concentration that produced 50% of the maximum response) for PGF2 alpha in CM was greater than in LM, indicating a lesser sensitivity of CM for this agent. Therefore, the heterogeneity between CM and LM extends to the effects of oxytocin and PGF2 alpha, further emphasizing the importance of distinguishing between the two muscle layers in studies of uterine activity.
以往的研究表明，环形（CM）和纵形子宫肌层（LM）具有不同的生理和药理特性。为了确定催产素和前列腺素F2-α（PGF2α）的作用是否也存在这种差异，我们比较了这些药物对妊娠第15、17和21天（足月）大鼠的CM和LM自发收缩的影响。两种药物在所有妊娠天数均刺激CM和LM，但反应如下不同：1）CM对催产素的反应在第15和17天是全或无的，对第15天的PGF2α是全或无的，仅在足月时对两种药物的反应是分级的；2）LM对两种药物的反应总是分级的；3）CM对催产素的最大反应总是小于LM，对PGF2α的最大反应除足月时大于LM外，在CM中小于LM；4）CM中PGF2α的EC50（产生最大反应50%的有效浓度）大于LM，表明CM对该药物的敏感性较低。因此，CM和LM之间的异质性扩展到催产素和PGF2α的作用，进一步强调了在子宫活动研究中区分这两层肌肉的重要性。
