McEvoy J D, McVeigh C E, McCaughey W J, Hewitt S A
Residues Department, Department of Agriculture for Northern Ireland, Belfast.
Vet Rec. 1998 Sep 12;143(11):296-9. doi: 10.1136/vr.143.11.296.
A temporal study of the biliary elimination of endogenous 19-nortestosterone during two successive pregnancies was made in three cows with cannulated gall bladders. Bile samples were analysed for 17 beta-19-nortestosterone (beta-NT) and the 17 alpha-epimer (alpha-NT) by using high resolution gas chromatography and mass spectroscopy. No beta-NT was detected in any of the samples analysed. However, alpha-NT was detected from around 120 days of gestation in each of the cows. Peak concentrations were observed in the last week before calving and ranged from 9.5 to 36.7 ng/ml. After parturtion, the concentrations of alpha-NT declined rapidly and were undetectable by seven days after calving, and it was not detected again until after 120 days of gestation. The biliary concentrations of alpha-NT detected subsequently were similar to those observed in cattle several weeks after an exogenous injection of the synthetic ester beta-NT phenylpropionate.
对三头胆囊插管的奶牛在连续两次妊娠期间内源性19-去甲睾酮的胆汁排泄情况进行了一项时间研究。通过高分辨率气相色谱法和质谱分析法对胆汁样本中的17β-19-去甲睾酮（β-NT）和17α-差向异构体（α-NT）进行分析。在所分析的任何样本中均未检测到β-NT。然而，在每头奶牛妊娠约120天时检测到了α-NT。在产犊前最后一周观察到峰值浓度，范围为9.5至36.7 ng/ml。分娩后，α-NT的浓度迅速下降，在产犊后7天无法检测到，直到妊娠120天后才再次检测到。随后检测到的α-NT的胆汁浓度与外源注射合成酯β-NT苯丙酸酯数周后的牛体内观察到的浓度相似。
