Anaerobic metabolism effects

The effects of ROM on liver have already been discussed. The potential involvement of ROM in I/R injury is suggested by the finding that glycogen-depleted livers are more susceptible to ischaemic injury. This is thought to be related to accumulation of hypoxanthine during anaerobic metabolism, which serves as a substrate for XO and hence enhanced production of RDM (Younes and Strubelt, 1988). 

Collomp, K., Ahmaidi, S., Audran, M., Chanal, J. L., and Prefaut, C., Effects of caffeine ingestion on performance and anaerobic metabolism during the Wingate Test, International Journal of Sports Medicine, 12, 439, 1991. 

Beyond this point, during more severe exercise associated with anaerobic metabolism, minute ventilation increases faster than the rate of oxygen consumption, but proportionally to the increase in carbon dioxide production. The mechanism of the ventilatory response to severe exercise involves metabolic acidosis caused by anaerobic metabolism. The lactic acid produced under these conditions liberates an H+ ion that effectively stimulates the peripheral chemoreceptors to increase ventilation. 

Similarly, the regulation of PDK activity is modified in adult muscle PDC. For example, PDK activity is inhibited by pyruvate and propionate (metabolites elevated during anaerobic metabolism) and is less sensitive to stimulation by elevated NADH/NAD+ and acetyl CoA/CoA ratios (Fig. 14.2) (Thissen et al, 1986 Chen et al, 1998). The effects of NADH and acetyl CoA on PDK activity are mediated by the degree of E3-catalysed oxidation and E2-catalysed acetylation of the inner lipoyl domain of E2 (Roche and Cate, 1977 Rahmatullah and Roche, 1985, 1987 Ravindran et al, 1996 Yang et al, 1998), so that the regulation of this phenomenon is complex and involves multiple interacting components. 

Richard H. M., Eertman, Wouter Zurburg, Cor A. Schipper, Ben Sandee and Aad C. Smaal, (1996). Effects of PCB 126 and cadmium on the anaerobic metabolism of the mussel Mytilus edulis L. Comparative Biochemistry and Physiology Part C Pharmacology, Toxicology and Endocrinology Volume 113, Issue 2,261-212. 

However, if an anaerobic metabolism such as ethanol fermentation occurs in a fermentor in the presence of high concentration of glucose, the RQ value becomes larger than 1.0, known as the Crabtree effect. This is because CO2 evolves without O2 consumption as follows. 

Tesniere, C., Baumes, R., Bayonove, C., and Flanzy, C. (1989). Effect of simulate alcoholic fermentation on aroma components of grape berries under anaerobic metabolism. Am. ]. Enol. Viticult. 40,183-188. 

Another report has provided more details from physical assessments and laboratory and radiological (MRI and MRS) data, and more information about the course of this heroin-related effect (21). The three cases showed raised concentrations of intracerebral lactate (reflecting mitochondrial dysfunction), which suggests a conversion of aerobic to anaerobic metabolism seen in hypoxic-ischemic conditions, including stroke. One patient recovered quite well after antioxidant therapy, supporting a metabolic effect of the heroin-related toxin a similar response to co-enzyme Q has been found in other mitochondrial disorders with a high CSF lactate. Thus, the authors recommended that although the role of antioxidant therapy in this condition is unclear, it may be prudent to administer oral co-enzyme Q supplemented with vitamins C and E to patients with this syndrome. 

An actual contribution of humic substances to metal oxide reduction in natural systems has not been demonstrated, and there are processes such as adsorption or decomposition that could limit their effectiveness. Kostka et al. (2002a) observed that AQDS additions elicited a larger increase in Fe(III) reduction by S. oneidensis growing on ferrihydrite than smectite clay minerals. This suggests that the influence of humic substances may depend on soil or sediment mineralogy. Nevertheless, there is ample evidence to suggest that a portion of the anaerobic metabolism that was previously attributed to direct enzymatic Fe(III) and Mn(IV) reduction was actually none-nzymatic reduction by microbially reduced humic substances. 

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