García M V, Hernández-Berciano R, López-Mediavilla C, Orfao A, Medina J M
Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Salamanca, Spain.
Exp Cell Res. 1997 Dec 15;237(2):403-9. doi: 10.1006/excr.1997.3804.
The effect of adrenaline on the control of respiratory activity of mitochondria from fetal hepatocytes in primary culture was studied. In the absence of adrenaline, the respiratory control ratio (RCR) of mitochondria increased during the first 3 days of culture due to a decrease in the rate of state 4 respiration. The presence of adrenaline in the incubation medium further increased the mitochondrial RCR through a decrease in the rate of respiration in state 4 and to an increase in the respiration rate in state 3. The effect of adrenaline was mimicked by dibutyryl-cAMP, forskolin, and isobutyl methyl xanthine. All these compounds increased cAMP concentrations, suggesting that cAMP may be involved in the effect of adrenaline. The increase in intracellular free Ca2+ concentrations caused by phenylephrine, vasopressin, or thapsigargin was also accompanied by an increase in the RCR, suggesting that both phenomena are associated. Dibutyryl-cAMP also increased free Ca2+ concentrations, suggesting that the effects of cAMP may be mediated by free Ca2+ concentrations. Adrenaline, dibutyryl-cAMP, phenylephrine, vasopressin, and thapsigargin promoted adenine nucleotide accumulation in mitochondria; this may be an intermediate step in the activation of mitochondrial respiratory function. These results suggest that the stimulatory effect of adrenaline on mitochondrial maturation in cultured fetal rat hepatocytes may be exerted through a mechanism in which both cAMP and Ca2+ act as second messengers. It is concluded that the effect of adrenaline on mitochondrial maturation is exerted by both alpha- and beta-adrenergic mechanisms and is mediated by the increase in adenine nucleotide contents of mitochondria.
研究了肾上腺素对原代培养的胎儿肝细胞线粒体呼吸活性调控的影响。在无肾上腺素的情况下，培养的前3天线粒体的呼吸控制率（RCR）因状态4呼吸速率降低而升高。孵育培养基中存在肾上腺素，通过降低状态4的呼吸速率和增加状态3的呼吸速率，进一步提高了线粒体的RCR。二丁酰环磷腺苷（dibutyryl-cAMP）、福斯可林（forskolin）和异丁基甲基黄嘌呤（isobutyl methyl xanthine）模拟了肾上腺素的作用。所有这些化合物均增加了环磷腺苷（cAMP）浓度，提示cAMP可能参与了肾上腺素的作用。去氧肾上腺素（phenylephrine）、血管加压素（vasopressin）或毒胡萝卜素（thapsigargin）引起的细胞内游离Ca2+浓度升高也伴随着RCR的增加，提示这两种现象相关。二丁酰环磷腺苷也增加了游离Ca2+浓度，提示cAMP的作用可能由游离Ca2+浓度介导。肾上腺素、二丁酰环磷腺苷、去氧肾上腺素、血管加压素和毒胡萝卜素促进了线粒体中腺嘌呤核苷酸的积累；这可能是线粒体呼吸功能激活的中间步骤。这些结果提示，肾上腺素对培养的胎鼠肝细胞线粒体成熟的刺激作用可能通过cAMP和Ca2+均作为第二信使的机制发挥。得出结论：肾上腺素对线粒体成熟的作用通过α-和β-肾上腺素能机制发挥，并由线粒体腺嘌呤核苷酸含量增加介导。
