Mitochondrial ATP generation

Mitochondrial ATP generation for the processes that maintain essential physiological activities... 

Mitochondrial ATP generation (i.e. that from the cycle pins electton transfer) is necessary to support almost all biochemical or physiological processes that are essential to life, as follows ... 

The common factor in all these processes, which accounts for the need for mitochondrial ATP generation, is that they reqnire ATP utilisation either continuously or for prolonged periods, so that the most efficient process for the use of fuel to generate ATP is necessary. 

Examples of leisure activities that are supported by mitochondrial ATP generation... 

There are at least three ways in which mitochondrial ATP generation can be impaired mutations in mitochondrial DNA, mutations in nuclear DNA and effects of toxic compounds. The reactions in mitochondrial metabolism that are affected by some toxic compounds are described in Appendix 9.12. 

Atherosclerosis is not itself a disease but it can lead to a poor supply of blood to tissues/organs, which consequently impairs mitochondrial ATP generation and hence can interfere with the function of that tissue. This leads initially to iU health, but can become sufficiently severe to lead to disease and, eventually, to death (see Chapter 22). 

Figure 19.14 Diffusion of oxygen from the vaginal smooth muscle into the lumen of the vagina. Increased contractions of the smooth muscle during coitus and especially during an orgasm increase the flow of blood through the muscle and hence increase the diffusion of oxygen into the lumen, where it is reguired by spermatozoa for mitochondrial ATP generation (see below).

McCarthy NJ, et al. Inhibition of Ced-3/ICE-related proteases does not prevent ceU death induced by oncogenes, DNA damage, or the Bcl-2 homologue Bak. J. Cell Biol. 1997 136 215-227. Hirsch T, et al. The apoptosis-necrosis paradox. Apoptogenic proteases activated after mitochondrial permeability transition determine the mode of ceU death. Oncogene 1997 15 1573-1581. Leist M, et al. Inhibition of mitochondrial ATP generation by nitric oxide switches apoptosis to necrosis. Exp. Cell Res. 1999 249 396-403. 

Fig. 4 Mitochondrial permeability transition (MPT) can cause either severe ATP depletion and cell necrosis, or caspase activation and apoptosis, (a) Opening of the MPT pore allows a reentry of protons through the pore, thus bypassing ATP synthase and preventing mitochondrial ATP generation. MPT also causes an influx of water driven by the oncotic pressure of matrix proteins. The outer membrane ruptures from matrix swelling, (b) When MPT only occurs in some mitochondria, the unaffected organelles synthesize enough ATP to prevent necrosis, while the affected mitochondria release cytochrome c, which activates caspases to trigger apoptosis. However, when MPT occurs in all mitochondria, severe ATP depletion causes cell swelling, rupture of the cell plasma membrane and necrosis...

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