**17. The pathway of the phospholipase A2**

The phospholipase A2 (PLA2) uses the phospholipidic membrane as an underlayer for the production of arachidonic acid, prostaglandin – in particular the prostaglandin E2 (PGE2)- leukotrienes and thromboxanes. This enzyme is located in the sarcolemma, in the mitochon‐ drial membrane, in the cytosolic compartment and in the lysosomes (Van der Vusse et al., 1989). In particular we suppose that the PLA2 present in the mitochondrial membrane may be implied in the mechanisms that induce the loss of the homeostasis of Ca++ (Cheah and Cheah, 1985). Likewise an increase of the concentrate of intracellular Ca++ would involve an activation of PLA2(Vane and Botting, 1987) The arachidonic acid and the lysophospholipids produced by the activation of PLA2, would cause a destabilization of the membrane structure assuming, in such a way, an important role in the field of autogenic processes following the harmful event (Jackson and Edwards, 1986; Chang et al., 1987). In addition the PLA2 would contribute to the loss of intramuscular enzymes observable in a muscular injury (Jackson et al., 1987). It is interesting to know that the PLA2 is one of the most important active principals of snake and bee poison. In fact the injection of poison of the coral snake (*Micrurus fulvius*) in the muscle of a mouse, provokes similar damage to that of an eccentric contraction (Arroyo et al., 1987) even if we need to underline the fact that the muscular necrosis induced by the snake's poison is much faster and larger than that seen in eccentric exercise. It is enough to think that an injection of only two micrograms of poison of the Australian tiger snake (*Notechis scutatus*) on rat muscle, leads to the total destruction of fiber in only 24 hours (Harris, 1989). It is also interesting to know that PLA possesses a protective role regarding oxidative stress (Van Kuijk et al., 1987)

The last two phases, of repair and re-modeling, are usually associated or overlapping (Kalimo

Etiology, Biology and Treatment of Muscular Lesions

http://dx.doi.org/10.5772/56602

29

The processes of muscular repair are completed in a period of about three weeks during which follow precise and expiring biological stages which we can schematically illustrate in six

**Second post-lesion day**: the necrotic parts of muscular fibers have been removed by the macrophages whereas, con‐ textually, the formation, on behalf of the fibers-blasts, of the healing connective tissue inside the central zone (CZ) has

**Third day**: the satellite cells have already started their activation which takes place inside the cylinders of the basal

et al., 1997).

started.

lamina in the zone of repair (RZ).

**19. The three post-lesion weeks**

fundamental phases as follows:
