Subcellular fractions of smooth muscle. Isolation, substrate utilization and Ca++ transport by main pulmonary artery and mesenteric vein mitochondria.
Subcellular fractions of smooth muscle. Isolation, substrate utilization and Ca++ transport by main pulmonary artery and mesenteric vein mitochondria.
复制标题
平滑肌的亚细胞部分。
DOI：
10.1016/0003-9861(75)90162-9
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发表时间：
1975
影响因子：
3.9
通讯作者：
A. Somlyo
中科院分区：
文献类型：
--
作者：
J. Vallières;A. Scarpa;A. Somlyo
在牛血清白蛋白存在下，从牛肠系膜静脉和主肺动脉制备线粒体。标准制剂含有30%到60%的线粒体蛋白。用极谱法测底物氧化速率。琥珀酸氧化速率(O2/m in/mg)分别为(117.1±16)和(92.3±13)nmol/m in/mg。其他底物的氧化速度则不那么快。在EDTA存在和不存在的情况下制备的血管平滑肌线粒体的钙含量远高于所有其他来源的线粒体。用双波长技术测量呼吸支持钙摄取的初始速度。在1μm Ca~(2+)时，速率较慢，但到25μm Ca~(2+)时，速率几乎呈线性增加。肺主动脉和肠系膜静脉线粒体的钙转运速度在75μm时达到最大值(分别为12和4nmoL/S/mg)，在17μm时达到半峰值，肠系膜静脉的钙转运速率均低于主肺动脉线粒体。在不解偶联的情况下，血管平滑肌线粒体可耐受高达210nmoL的线粒体蛋白。这些发现从细胞内钙离子水平的生理调节角度进行了讨论。
Mitochondria were prepared from bovine mesenteric vein and main pulmonary artery in the presence of bovine serum albumin. Standard preparations contained between 30 and 60% of mitochondrial protein. Rates of substrate oxidation were measured polarographically. Succinate was oxidized at rates of 117.1±16 and 92.3±13 nmol of (O 2/min/mg of main pulmonary artery and mesenteric vein mitochondrial protein, respectively. Other substrates were oxidized less rapidly. The calcium content of vascular smooth muscle mitochondria prepared in the presence and absence of EDTA was found to be much higher than in mitochondria from all other sources. Initial velocities of respiration-supported calcium uptake were measured by dual-wavelength techniques. Rates were slow at 1 μ m Ca 2+ but increased almost linearly up to 25 μ m Ca 2+. The maximal velocities (12 and 4 nmol of Ca 2+/s/mg of main pulmonary artery and mesenteric vein mitochondrial protein, respectively) were observed at 75 μ m Ca 2+, and the half-maximal transports occurred at 17 μ m. At all [Ca 2+] tested, the rate of Ca 2+ transport was lower by mesenteric vein than by main pulmonary artery mitochondria. Vascular smooth muscle mitochondria can tolerate as much as 210 nmol of Ca 2+ mg of mitochondrial protein without uncoupling. These findings are discussed in terms of physiological regulation of cytosolic calcium levels in smooth muscle.