Maintenance of mitochondrial volume and the effects of phosphate and ATP in producing swelling and shrinking

✍ Scribed by W. Bartley; B. Dean; W. Ferdinand

• Book ID: 104155145
• Publisher: Elsevier Science
• Year: 1969
• Tongue: English
• Weight: 740 KB
• Volume: 24
• Category: Article
• ISSN: 0022-5193
• DOI: 10.1016/s0022-5193(69)80045-7

✦ Synopsis

Hypotheses that have been put forward to explain why mitochondria do not swell when placed in nominally hypo6smotic solutions are examined critically in the light of known experimental data. A metabolically driven ion-pump is ruled out as the means of maintaining mitochondrial volume because of permeability considerations and the fact that the total solute concentration is higher inside than outside the mitochondrion. Similarly, a water-pump is ruled out because of the excessive amount of energy it would require, far more than that available from the metabolism of the organelle. Various other possibilities can also be discarded, but there remains a choice between, or a combination of, two possible mechanisms. Excess internal solutes may be bound or compartmented in a way that reduces their activity, or alternatively the internal hydrostatic pressure may be raised to offset the tendency to osmotic swelling. In the latter case a rigid outer casing would be needed to hold the internal pressure. Some experimental evidence in favour of the latter hypothesis is presented.