Electron fluxes are constant within cellular metabolism. Donating or accepting electrons, either naked or as hydrogen atoms, is one of the most important properties of bioenergetic networks. These redox reactions fulfill key physiological phenomena such as cellular growing, phenotypic differentiation, nutritional adaptations and redox‐dependent cellular signaling, but when they became unregulated, serious pathologies such as degenerative diseases and metabolic disorders arise. The liver being an important metabolic organ, redox reactions play a strategic role in its main functions: processing of nutrients, fasting response, xenobiotic managing and circadian activity. However, liver is also very sensitive to compounds that disturb redox state such as ethanol, CCl4, aflatoxins, among others, as well as to stressors such as hypercaloric diets, endocrine disruptors and stressful life situations. This chapter reviews concepts related to redox reactions in the liver, including metabolic aspects of reactive oxygen species (ROS), prooxidant and antioxidant subcellular systems, alterations produced by hepatotoxins, adaptations to experimental surgical protocols such as portacaval anastomosis, and participation in cancer. It is out of question that for a better comprehension of the physiopathological events in the liver and other metabolic organs, the more complete understanding of the roles played by redox reactions will be a necessity.
Part of the book: Redox
Purinergic signaling is a sophisticated system of elements in which ATP and related molecules function as intercellular messengers. When ATP is released into the extracellular space, it activates specific receptors that belong to the P2 family. In parallel, ectonucleotidases transform ATP in its dephosphorylated metabolites including adenosine, which stimulates P1 receptors. The activity of both receptors influences various cellular processes. Moreover, metabolic conditions are concatenated with purine signaling to conform a dynamic and continuous informational network. The role of purinergic signaling in ovarian cells has been investigated, for instance, it is known that cells conforming the follicle express functional receptors that modulate basic cellular process such as proliferation, induction of apoptotic cell death, and steroidogenesis. In this chapter, we review contemporary information on purinergic action in ovarian cell physiology and state its relevance in this field.
Part of the book: Adenosine Triphosphate in Health and Disease