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KMID : 0378019730160010101
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New Medical Journal
1973 Volume.16 No. 1 p.101 ~ p.107
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Effects of Prenatal Anoxic Exposure on Leucine-311 Incorporation by the Osteoblast, Chondrocyte, Hepatic Parenchyma Cells and Kidney in Rat Neonates
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Abstract
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In each experiment 3 pregnant Sprague-Dawley rats were subjected to total anoxia for a period of 20 minutes in a two periods of 10 min. and 10 min. respectively. The two insults were separated by a 15 min. recovery period, by placing them in a bell jar which was flushed with a continued flow of purified nitrogen. The oxygen content in the jar, judged by use of a Westinghouse oxygen analyzer, was 30 to 40 ppm. Following the exposure to anoxia, the rats were allowed to give natural birth until day 22 of gestation. If the delivery was not made by 22 days, however, the pregnant rats were anesthetized with ether and the fetuses were removed. These subjects were regarded as being equal to those neonates which were delivered naturally. The neonatal rats were used within hours after delivery so that none of them would have experienced suckling. For each experiment, a total of 9 selected neonates were used for radioautographic preparation. These consist of 3 litter mates each from the 3 experimental groups representing animals insulted on days 12, 15 and 18 of fetal life. All animal were maintained on purina Lab. chow and given tap water ad libitum.
Each of the neonatal rats was intraperitoneally injected with DL-Leucine-4,5-3H in tht amount of 10rc/gin body weight. The specific activity of the labelled amino acid was 3.90c/m M. One-animal from each of the 4 groups was sacrificed at 15, 60 or 120 minutes following the injection of leucine 3H.
The tissues were rapidly excised, fixed for 24 hours in 10% neutral formalin and embedded in parlodion and paraplast in the standard manner.
The results were as follows:
1. Following the exposure to anoxia, the synthesis of proteins was suppressed in osteoblast chondro cytes; hepatic parenchymal cells and kidney.
2. In animals sacrificed at 1 hour and 2 hours after the injection of the radioactive amino acid, the
number of grains per cell is the lowest in animals insulted on day 12.
3. Although a significant difference between the experimental and control animals is observed in rats
injected with radioactive precursor 15 minutes before the sacrifice, the difference is most pronounced
in animals sacrificed at 1 hour and 2 hours.
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