Corbet A J, Flax P, Rudolph A J
J Appl Physiol. 1976 Jul;41(1):7-14. doi: 10.1152/jappl.1976.41.1.7.
After opening the maternal abdomen under methoxyflurane anesthesia, fetal rabbits 25.5-28.5 days gestation were given an intraperitoneal injection of pilocarpine (150 mg/kg) or saline through the intact uterine wall. They were delivered by hysterotomy and sacrificed without breathing 2.5 h later. Newborn rabbits 29.5 days gestation received an injection of pilocarpine or saline at birth and breathed 30-120 min. Other newborn rabbits 29.5 days gestation were alternately sacrificed at birth or after breathing 30 min. Static pressure-volume curves with air showed decreased recoil and improved air retention on deflation in fetal rabbits 25.5-27.5 days injected with pilocarpine. There was no change in the static pressure-volume curve of lungs filled with saline. The data suggest that pilocarpine reduced surface tension by producing secretion of surfactant into air spaces. No change in lung recoil occurred with pilocarpine at 28.5 days, or with pilocarpine or breathing at 29.5 days. This may mean that air spaces at 28.5-29.5 days contained optimal surfactant, so further secretion of surfactant stimulated by pilocarpine or breathing failed to reduce surface tension.
在甲氧氟烷麻醉下打开母兔腹腔后，通过完整的子宫壁给妊娠25.5 - 28.5天的胎兔腹腔注射毛果芸香碱（150毫克/千克）或生理盐水。通过子宫切开术将它们取出，2.5小时后在未呼吸的状态下处死。妊娠29.5天的新生兔在出生时注射毛果芸香碱或生理盐水，并呼吸30 - 120分钟。其他妊娠29.5天的新生兔在出生时或呼吸30分钟后交替处死。注入毛果芸香碱的妊娠25.5 - 27.5天的胎兔的肺充气静态压力 - 容积曲线显示，呼气时肺回缩力降低，气体潴留改善。充满生理盐水的肺的静态压力 - 容积曲线无变化。数据表明，毛果芸香碱通过促使表面活性物质分泌到气腔中降低了表面张力。在28.5天时，毛果芸香碱对肺回缩力无影响；在29.5天时，毛果芸香碱或呼吸对肺回缩力也无影响。这可能意味着在28.5 - 29.5天时气腔中含有最佳量的表面活性物质，因此毛果芸香碱或呼吸刺激产生的表面活性物质进一步分泌未能降低表面张力。
