12 در انبار
An atom or a group of atoms that contains one or more unpaired electron(s) is termed a free radical, which is often a highly reactive and unstable molecule. Two groups of these radical molecules are often classified as reactive oxygen and reactive nitrogen species, respectively. Stabilisation of these radicals requires electron donation from proteins, lipids and DNA which oftentimes leads to degradation and damage to these molecules.
Owing to the potential for cellular damage, much controversy was created by initial reports that indicated that physical exercise increased the production of reactive oxygen species (ROS) (Dillard et al. 1978). This initial work did not reveal the specific location, but later work revealed the contracting skeletal muscle to be a prominent source of ROS (Davies et al. 1982).
Years later, it was also revealed that contracting muscles also produced nitric oxide (NO), the predominant parent molecule of reactive nitrogen species (Balon and Nadler 1994), and a number of well-constructed review articles since then have confirmed the contribution of skeletal muscle to the production of both ROS and reactive nitrogen species (Powers and Jackson 2008, Jackson 2009, Powers et al. 2011).
12 در انبار