Lahav M, Schoenfeld N, Epstein O, Greenblat Y, Atsmon A
Isr J Med Sci. 1984 Mar;20(3):191-6.
It is known that fasting may provoke an acute attack in patients with latent hepatic porphyrias. We examined the influence of fasting on some aspects of heme synthesis in rats. Urinary excretion of both uroporphyrin and coproporphyrin, as well as fecal elimination of protoporphyrin and coproporphyrin, were increased on fasting. These biochemical aberrations resemble those found in subjects with latent porphyria variegata, suggesting that fasting rats may constitute an experimental model for latent variegate porphyria. The administration of phenobarbitone had a pronounced, synergistic effect on the urinary excretion of porphyrins. The activity of delta-aminolevulinic acid synthase (ALAS) and the concentration of cellular heme were determined in homogenates and subcellular fractions of the livers of fasting rats. A marked increase in the concentration of heme in the homogenate, the nuclei and the postmicrosomal supernatant fractions was observed. ALAS activity in the homogenate and the supernatant fraction increased while that in the mitochondria decreased. The possible relationship of these results to the human disease is discussed.
众所周知，禁食可能会诱发潜伏性肝卟啉病患者的急性发作。我们研究了禁食对大鼠血红素合成某些方面的影响。禁食时，尿卟啉和粪卟啉的尿排泄以及原卟啉和粪卟啉的粪便排泄均增加。这些生化异常类似于杂合性潜伏性卟啉病患者中发现的异常，表明禁食大鼠可能构成杂合性潜伏性卟啉病的实验模型。苯巴比妥的给药对卟啉的尿排泄有显著的协同作用。在禁食大鼠肝脏的匀浆和亚细胞组分中测定了δ-氨基-γ-酮戊酸合酶（ALAS）的活性和细胞血红素的浓度。观察到匀浆、细胞核和微粒体后上清液组分中血红素浓度显著增加。匀浆和上清液组分中的ALAS活性增加，而线粒体中的ALAS活性降低。讨论了这些结果与人类疾病的可能关系。
