Samuels E R, Scott J E
Department of Anatomy, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Life Sci. 1995;57(17):1557-68. doi: 10.1016/0024-3205(95)02131-2.
Evidence indicates that Ca(+2)-phosphatidylserine-dependent protein kinase C (PKC) is involved in regulation of surfactant secretion. This study was done to examine PKC activity in lung as surfactant synthesis and secretion is initiated, and at birth and to compare these enzyme levels with those in the adult lung. NZW rabbits were used. Fetal and adult lungs were fractionated into subcellular compartments including a lamellar body fraction, which represents intracellular surfactant. The time course for microsomal enzyme activity was compared between 24th gestational day and adult rabbit lung. The reactivity appeared similar in both fractions. PKC specific activity displayed a prominent peak between the 27th and 30th gestational days in total homogenate and lamellar bodies. Specific activity was also high in nuclear, mitochondrial and microsomal fractions the day prior to birth. Adult levels were similar or higher. Total PKC activity was high during late gestation but declined sharply the day prior to birth. A marked increase was present on the first postnatal day. In contrast lamellar bodies displayed a peak in activity between the 27th and 30th gestational days followed by a decline to adult levels. Delipidation of lamellar body fraction indicated that the high enzyme activity in this fraction on the 27th gestational day was not artifactual. The changes observed in PKC in fetal, neonatal and adult lung indicate this enzyme activity changes in lung during the period of onset of surfactant synthesis and secretion during late gestation and may be associated with lamellar bodies, in 27th gestational day fetal lung.
有证据表明，钙（+2）-磷脂丝氨酸依赖性蛋白激酶C（PKC）参与表面活性剂分泌的调节。本研究旨在检查肺中PKC的活性，观察表面活性剂合成和分泌开始时、出生时的情况，并将这些酶水平与成年肺中的水平进行比较。使用了新西兰白兔。将胎儿和成年兔的肺分离成亚细胞区室，包括代表细胞内表面活性剂的板层小体部分。比较了妊娠第24天和成年兔肺微粒体酶活性的时间进程。两个部分的反应性看起来相似。在总匀浆和板层小体中，PKC比活性在妊娠第27天至第30天之间出现一个显著峰值。出生前一天，核、线粒体和微粒体部分的比活性也很高。成年水平相似或更高。总PKC活性在妊娠后期较高，但在出生前一天急剧下降。出生后第一天有明显增加。相比之下，板层小体的活性在妊娠第27天至第30天之间出现峰值，随后下降至成年水平。板层小体部分的脱脂表明，妊娠第27天该部分的高酶活性并非人为造成。在胎儿、新生儿和成年肺中观察到的PKC变化表明，在妊娠后期表面活性剂合成和分泌开始期间，该酶活性在肺中发生变化，并且可能与妊娠第27天胎儿肺中的板层小体有关。
