Avner D L, Berenson M M
Am J Physiol. 1982 Apr;242(4):G347-53. doi: 10.1152/ajpgi.1982.242.4.G347.
The major route of protoporphyrin elimination is biliary secretion. To clarify the nature of the secretory process, maximal canalicular secretion of protoporphyrin was determined under basal conditions and after treatment with various choleretics. The maximal secretion of protoporphyrin under basal conditions was 0.07 +/- 0.01 micrograms.min-1.100 g body wt-1. Infusion of physiological amounts of sodium taurocholate increased protoporphyrin secretion 13-fold (0.90 +/- 0.02), primarily by increasing the biliary protoporphyrin concentration. Biliary protoporphyrin secretion tended to plateau in spite of a continued rise in both biliary bile acid secretion and concentration. Infusion of sodium dehydrocholate increased protoporphyrin secretion, but to only 35% of that achieved by sodium taurocholate. Ethacrynic acid and phenobarbital increased bile flow over controls but failed to enhance protoporphyrin transport. Thus, canalicular secretion of protoporphyrin was maximally enhanced by micelle-forming bile acids and unaffected by nonbile acid choleretics. The observed limitation of protoporphyrin secretion may be related to achievement of a canalicular transport maximum or to a toxic effect of protoporphyrin on the transport process.
原卟啉的主要消除途径是胆汁分泌。为了阐明分泌过程的性质，在基础条件下以及用各种利胆剂处理后，测定了原卟啉的最大胆小管分泌量。基础条件下原卟啉的最大分泌量为0.07±0.01微克·分钟-1·100克体重-1。输注生理量的牛磺胆酸钠可使原卟啉分泌增加13倍（0.90±0.02），主要是通过增加胆汁中原卟啉的浓度。尽管胆汁中胆汁酸的分泌量和浓度持续升高，但胆汁中原卟啉的分泌趋于平稳。输注去氢胆酸钠可增加原卟啉的分泌，但仅为牛磺胆酸钠所达到水平的35%。依他尼酸和苯巴比妥使胆汁流量比对照组增加，但未能增强原卟啉的转运。因此，形成胶束的胆汁酸可最大程度地增强原卟啉的胆小管分泌，而非胆汁酸类利胆剂则无此作用。观察到的原卟啉分泌受限可能与达到胆小管转运最大值有关，或者与原卟啉对转运过程的毒性作用有关。
