Positional metabolism of benzo(a)pyrene in rat placenta and maternal liver. Comparison of induction effects

The biotransformation of [14C]benzo(a)pyrene (BP) was studied in vitro in the presence of microsomes prepared from isolated labyrinth and basal zone tissues of the rat placenta, as well as from maternal liver. Pregnant rats, day 14 of gestation, received beta-naphthoflavone (beta NF; 15 mg/kg, ip) or 3-methyl-cholanthrene (3MC; 30 mg/kg, ip). On day 15, placentae were dissected and microsomes were incubated with 17 microM [14C]BP and 2 mM NADPH. Metabolites formed in the incubation flasks were extracted and separated by HPLC utilizing a reverse phase column. Only trace BP metabolism occurred in basal zone microsomes from control, beta NF-, or 3MC-pretreated animals, as well as in labyrinth microsomes from control animals. In contrast, the preadministration of beta NF and 3MC increased labyrinth microsomal BP metabolism by 10- to 15-fold. Labyrinth and maternal liver microsomes from beta NF- and 3MC-treated animals actively converted BP to eight separate metabolites which co-chromatographed primarily with quinones and phenols. The overall formation of BP diol and phenolic metabolites by labyrinth microsomes was appreciably less than was observed for liver preparations. The very low activity of BP-4,5-oxide hydrolase in labyrinth microsomes compared to liver may in part explain the low level of formation of BP diols in placental microsomes. Labyrinth microsomes catalyzed the covalent binding of [3H]BP to calf thymus DNA, and this activity increased 5-fold following beta NF pretreatment. A comparison of induced tissues indicates that the amount of DNA binding in labyrinth microsomes is more extensive than would be expected by the level of total BP metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)     

新生儿重症呼吸道感染氧气雾化吸入疗效分析

新生儿重症呼吸系统感染引起的新生儿慢性肺部疾病、重症肺炎、胎粪吸入性肺炎,病情重,发展快,易导致呼吸衰竭,死亡率高. 常用的方法除抗炎、改善通气、纠正缺氧和上用呼吸机外，雾化吸入治疗也起到重要的辅助作用。传统的地塞米松超声雾化吸入治疗，疗效差，且具有许多副作用。     

Expression of functional postjunctional alpha 2-adrenoceptors in rabbit isolated distal saphenous artery--a permissive role for angiotensin II?

In the rabbit isolated distal saphenous artery, the population of postjunctional adrenoceptors is of the alpha 1 variety under normal in vitro experimental conditions, based on the potency order of selective agonists and on the effects of the antagonists prazosin and rauwolscine against responses to UK-14304. Angiotensin II (A II, 0.05 microM) however, without affecting resting baseline tension, markedly enhanced responses to UK-14304, particularly at low concentrations. This previously unseen component of the response to UK-14304 was resistant to prazosin (0.1 microM) but susceptible to rauwolscine (1 microM). A II would therefore appear to have a permissive role for the expression of a quiescent population of postjunctional alpha 2-adrenoceptors in the rabbit distal saphenous artery.     

Ca^＋＋对链霉素抗原—抗体反应的抑制作用

为探讨临床中使用钙制剂抢救链霉素过敏休克病人有良好效果的原因,由被动血凝试验、被动皮肤过敏试验和ELISA法证实,Ca~( )可以抑制链霉素抗原-抗体的反应。这种抑制作用是通过Ca~( )链霉素抗原结合,封闭链霉素抗原决定簇来加以实现的。     

Modulation of neurotransmission in the guinea-pig vas deferens by capsaicin: involvement of calcitonin gene-related peptide and substance P.

1. The effects of capsaicin, calcitonin gene-related peptide and substance P were studied via three parameters in the guinea-pig vas deferens: the overflow of ATP and of tritiated noradrenaline, the mechanical responses to field stimulation and the mechanical responses to exogenous noradrenaline and alpha, beta-methylene ATP. 2. At 2 Hz, capsaicin inhibited the stimulus-evoked release of ATP, whereas it was without effect on the release of noradrenaline. At 20 Hz capsaicin did not affect the release of either of the cotransmitters. Capsaicin enhanced responses to alpha, beta-methylene ATP, but not to exogenous noradrenaline. 3. Calcitonin gene-related peptide, like capsaicin, inhibited the release of ATP, but not noradrenaline at 2 Hz and was without effect on release at 20 Hz. However, calcitonin gene related peptide inhibited responses to alpha, beta-methylene ATP and was without effect on responses to exogenous noradrenaline. 4. Substance P had no effect on the release of either noradrenaline or ATP at either frequency. However, like capsaicin it enhanced responses to alpha, beta-methylene ATP and was without effect on exogenous noradrenaline. 5. These results suggest that the actions of capsaicin on the guinea-pig isolated vas deferens are mediated via the release of both calcitonin gene-related peptide and substance P. Furthermore, as capsaicin and calcitonin gene-related peptide prejunctionally modulate purinergic, but not noradrenergic transmission, this suggests that the mechanisms for the storage and release of the sympathetic co-transmitters noradrenaline and ATP may not be the same.