[Transport of ions in mitochondria in connection with osmotic concentration of media]

Studies on mitochondria has revealed apparent violation of laws of osmosis, apparently, related to ion transport. In this context, we studied changes in the content of potassium, sodium, magnesium, and calcium in mitochondria from wheat (Triticum aestivum L.) roots incubated in the buffer without the substrate with 0.3 or 0.5 M sucrose as well as potassium, and phosphate. The most pronounced changes were observed for potassium. Potassium arrival to mitochondria was more active at 0.5 than 0.3 M sucrose. The direction of the cation transport depended on its content in the initial buffer. At the certain threshold level, the inflow was replaced with the outflow; this threshold was lower at 0.3 than 0.5 M sucrose. Magnesium was also released from mitochondria; its stable outflow was primarily observed at its lower initial content in the suspension at 0.3 rather than 0.5 M sucrose. The obtained data demonstrated that the apparent violation of laws of osmosis was false and resulted from ion transport. Passive ion transport as a possible mechanism of adaptation to osmotic properties of the external medium is discussed.