Naftalin N J, Phear W P, Goldberg A H
Anesthesiology. 1976 Jul;45(1):31-8. doi: 10.1097/00000542-197607000-00007.
Isolated strips of mid-pregnant and postpartum rat myometrium were rendered functionally Ca2+-free by exposure to a Ca2+-free modified Krebs-bicarbonate solution containing 1 mM EGTA. The muscle strips were then exposed to 2.25 mM Ca2+ for periods of 15 to 600 seconds for the mid-pregnant tissues and one 120-second period for the postpartum tissues. At the end of each exposure, Ca2+ was removed and simultaneously each muscle was depolarized with 125 mM K2SO4. Isometric tension changes in the muscles were measured with and without 0.5 per cent halothane. In the mid-pregnant muscles, halothane diminished the initial tension development in response to Ca2+ by approximately 50 per cent, regardless of the duration of Ca2+ exposure. The contractile response of these muscles to depolarization with K2SO4 was reduced 10 per cent by 0.5 per cent halothane; this was probably due to reduction in transmembrane influx of Ca2+. In the postpartum muscles, the initial tension development in response to Ca2+ was threefold greater than in mid-pregnant muscles and was reduced 25 per cent by halothane. These tissues failed to develop by any tension in response to K2SO4. The most likely explanation for the effect of halothane is that it reduces the transmembrane influx of Ca2+ in both types of tissues, but that the postpartum sarcoplasmic reticulum present less competition for intracellular Ca2+ than pregnant sarcoplasmic reticulum.
将妊娠中期和产后大鼠子宫肌层的分离条带暴露于含有1 mM乙二醇双四乙酸（EGTA）的无钙改良克雷布斯 - 碳酸氢盐溶液中，使其在功能上处于无钙状态。然后，将妊娠中期组织的肌条暴露于2.25 mM钙离子中15至600秒，产后组织暴露于2.25 mM钙离子中120秒。每次暴露结束时，去除钙离子，同时用125 mM硫酸钾使每条肌肉去极化。分别在有和没有0.5%氟烷的情况下测量肌肉的等长张力变化。在妊娠中期的肌肉中，无论钙离子暴露时间长短，氟烷使对钙离子的初始张力发展降低约50%。0.5%氟烷使这些肌肉对硫酸钾去极化的收缩反应降低10%；这可能是由于跨膜钙离子内流减少所致。在产后肌肉中，对钙离子的初始张力发展比妊娠中期肌肉大三倍，且氟烷使其降低25%。这些组织对硫酸钾没有产生任何张力。氟烷作用最可能的解释是，它减少了两种类型组织中的跨膜钙离子内流，但产后肌浆网对细胞内钙离子的竞争比妊娠肌浆网少。
