Brady A M, Hasmall R L, Elcombe B M
Biochemical Toxicology Section, Zeneca Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire SK10 4TJ, UK.
Toxicol In Vitro. 1993 Sep;7(5):587-93. doi: 10.1016/0887-2333(93)90092-j.
The ability of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC), 3,5-diethoxycarbonyl-4-ethyl-1,4-dihydro-2,6-dimethyl pyridine (EDDC) and griseofulvin to induce porphyria in primary cultures of mouse and rat hepatocytes was determined. Exposure of mouse hepatocytes to DDC, EDDC or griseofulvin (5-100 mum) for 4 days resulted in a marked inhibition of ferrochelatase activity (up to 95%). However, whereas exposure of rat hepatocytes to DDC or EDDC (5-100 mum) for 4 days also resulted in marked inhibition of ferrochelatase activity (up to 96%), exposure to griseofulvin (5-100 mum) had no effect. DDC, EDDC and griseofulvin induced porphyrin accumulation in both mouse and rat hepatocyte cultures. In mouse hepatocyte cultures exposed to each xenobiotic the porphyrin that accumulated was predominantly protoporphyrin. In rat hepatocyte cultures exposed to DDC or EDDC the porphyrin that accumulated was also predominantly protoporphyrin, whereas following exposure to griseofulvin it was coproporphyrin. Time course studies confirmed that in rat hepatocyte cultures exposed to griseofulvin (25 or 100 mum) over a 4-day exposure period, ferrochelatase activity was not inhibited and coproporphyrin was always the predominant porphyrin accumulating (45-72% of total). Addition of 5-aminolaevulinic acid to mouse or rat hepatocyte cultures (10-1000 mum) also resulted in marked accumulation of porphyrin but whereas uroporphyrin accumulated in mouse hepatocyte cultures, coproporphyrin accumulated in rat hepatocyte cultures. These studies demonstrated that the hepatic porphyrias produced by the dihydropyridines and griseofulvin can be modelled in vitro in primary cultures of hepatocytes. Furthermore, the species differences in sensitivity of mouse and rat hepatocyte cultures in vitro to inhibition of ferrochelatase activity by griseofulvin mirrors, and therefore probably explains, the species differences in porphyria observed in vivo.
测定了3,5 - 二乙氧羰基 - 1,4 - 二氢可力丁（DDC）、3,5 - 二乙氧羰基 - 4 - 乙基 - 1,4 - 二氢 - 2,6 - 二甲基吡啶（EDDC）和灰黄霉素在原代培养的小鼠和大鼠肝细胞中诱导卟啉症的能力。将小鼠肝细胞暴露于DDC、EDDC或灰黄霉素（5 - 100 μmol）4天，导致亚铁螯合酶活性显著抑制（高达95%）。然而，虽然将大鼠肝细胞暴露于DDC或EDDC（5 - 100 μmol）4天也导致亚铁螯合酶活性显著抑制（高达96%），但暴露于灰黄霉素（5 - 100 μmol）则没有影响。DDC、EDDC和灰黄霉素在小鼠和大鼠肝细胞培养物中均诱导了卟啉积累。在暴露于每种外源性物质的小鼠肝细胞培养物中，积累的卟啉主要是原卟啉。在暴露于DDC或EDDC的大鼠肝细胞培养物中，积累的卟啉也主要是原卟啉，而在暴露于灰黄霉素后则是粪卟啉。时间进程研究证实，在4天暴露期内将大鼠肝细胞培养物暴露于灰黄霉素（25或100 μmol），亚铁螯合酶活性未受抑制，粪卟啉始终是积累的主要卟啉（占总量的45 - 72%）。向小鼠或大鼠肝细胞培养物中添加5 - 氨基乙酰丙酸（10 - 1000 μmol）也导致卟啉显著积累，但在小鼠肝细胞培养物中积累的是尿卟啉，而在大鼠肝细胞培养物中积累的是粪卟啉。这些研究表明，二氢吡啶类和灰黄霉素产生的肝卟啉症可以在肝细胞原代培养物中进行体外模拟。此外，体外小鼠和大鼠肝细胞培养物对灰黄霉素抑制亚铁螯合酶活性的敏感性差异反映了，因此可能解释了，体内观察到的卟啉症的物种差异。
