Candipan R C, Sjöstrand F S
J Ultrastruct Res. 1984 Dec;89(3):249-60. doi: 10.1016/s0022-5320(84)80041-6.
When analyzing mitochondria isolated in a sucrose medium that had been embedded for thin sectioning according to one low denaturation embedding technique, large intracristal spaces were present in close to 90% of the mitochondria. The two crista membranes were closely apposed in only 40% of all cristae. When the mitochondria were transferred to an incubation medium, the percentage of mitochondria with intracristal spaces was reduced to 40%. About 90% of all cristae were lacking any space separating the two crista membranes. The presence of inorganic phosphate in the medium was required for the closing of the intracristal spaces. The percentage of cristae lacking an intracristal space remained the same after addition of substrate for respiration (state 4) and of ADP (state 3). Inhibition or uncoupling of respiration led to an increase in the percentage of intracristal spaces, showing that oxidative phosphorylation is required to maintain the crista membranes closely apposed. The appearance and disappearance of the intracristal spaces was an indication of water movements across the crista membranes. The mean volume of the mitochondria increased 33% when they were transferred from the sucrose medium to the incubation medium, showing that the removal of water from the cristae was not caused by a passive osmotic effect. Addition of substrate made the volume decrease by 28%. After further addition of ADP, the volume decreased another 23%. No change in volume was associated with inhibition or uncoupling of respiration. The observations revealed that water can move into or out of the cristae independently of water movement out from the entire mitochondrion. Therefore, the water moving out from or into the cristae is translocated across the cristae membrane. The observations are interpreted to reveal the presence of a mechanism that actively prevents water from accumulating in the crista membrane. This mechanism allows for a low water activity to be maintained within the membrane. The variations in the frequency of intracristal spaces occurred without any simultaneous changes in the width of the space appearing between the two surface membranes after isolation of the mitochondria. The observations, therefore, do not agree with the concept that there is an outer compartment that communicates freely with intracristal spaces.
当分析按照一种低变性包埋技术包埋用于超薄切片的蔗糖培养基中分离出的线粒体时，近90%的线粒体存在大的嵴内间隙。在所有嵴中，只有40%的两个嵴膜紧密贴合。当线粒体转移到孵育培养基中时，有嵴内间隙的线粒体百分比降至40%。所有嵴中约90%不存在分隔两个嵴膜的间隙。培养基中无机磷酸盐的存在是嵴内间隙闭合所必需的。添加呼吸底物（状态4）和ADP（状态3）后，没有嵴内间隙的嵴的百分比保持不变。呼吸抑制或解偶联导致嵴内间隙百分比增加，表明需要氧化磷酸化来维持嵴膜紧密贴合。嵴内间隙的出现和消失表明水跨嵴膜的移动。当线粒体从蔗糖培养基转移到孵育培养基时，线粒体的平均体积增加了33%，表明从嵴中去除水不是由被动渗透作用引起的。添加底物使体积减少了28%。进一步添加ADP后，体积又减少了23%。体积变化与呼吸抑制或解偶联无关。这些观察结果表明，水可以独立于从整个线粒体流出的水而进出嵴。因此，进出嵴的水是跨嵴膜转运的。这些观察结果被解释为揭示了一种主动防止水在嵴膜中积累的机制的存在。这种机制允许在膜内维持低水活性。嵴内间隙频率的变化发生时，线粒体分离后两个表面膜之间出现的间隙宽度没有任何同时发生的变化。因此，这些观察结果与存在一个与嵴内间隙自由连通的外室的概念不一致。
