This study was aimed to evaluate the role of p38
mitogen-activated
protein (MAP)
kinase in the degradation of membrane
phospholipids and the regulation of cytosolic
phospholipase A2 (cPLA2) in cardiac myocytes after
burn trauma. In an in vivo study, rats were randomized into four groups: (1)
sham-
burn group, (2)
burn group (40% total body surface area full-thickness
burn), (3)
burn +
SB203580 group, and (4)
burn + vehicle group. The rats from each group were killed at varying times after
burn to examine the
p38 MAP kinase activation (by means of Western blot analysis and immunohistochemical assay), the expression of cPLA2 (by means of
reverse transcriptase polymerase chain reaction), the level of cardiac membrane
phospholipids, and the level of the remaining
creatine kinase-MB (CK-MB)
isoenzyme in the heart. These studies showed that
burn resulted in a significant decrease in the level of cardiac membrane
phospholipids from 3 to 24 h after
burn, which was paralleled with a persistent activation of
p38 MAP kinase and an increased expression of cPLA2 in the heart.
SB203580, a selective inhibitor of
p38 MAP kinase, inhibited the activation of cardiac
p38 MAP kinase, suppressed the
burn-induced upregulation of cPLA2 and the increased PLA2 activity, and prevented
burn-induced decrease in the levels of the cardiac membrane
phospholipids and the remaining
creatine kinase-MB isoenzyme. In addition, the in vitro treatment of cardiac myocytes with
SB203580 also abolished the upregulation of cPLA2 and the disturbance of
phospholipid homeostasis elicited by
hypoxia and
burn serum challenge. Taken together, these results have demonstrated for the first time that
p38 MAP kinase is involved in
burn-induced membrane
phospholipids degradation in cardiac myocytes, at least in part through the regulation of cPLA2.