[Role of p38 mitogen activated protein kinase in the regulation of membrane myocardiac phospholipids degradation in early stage of severe burn rat].
OBJECTIVE
To investigate the role of p38 mitogen activated protein kinase ( p38 MAPK) in the regulation of cytosolic phospholipase A2 ( cPLA2 ) expression and degradation of membrane phospholipids in myocardium in early stage of burn rats.


METHODS
Wistar rats were randomized into normal group (n = 8), burn(n =40) , burn and SB203580(n = 16), burn and isotonic saline( n = 16) groups, with 8 rats at each time-points. There were 5 time-points in burn group, and 2 time-points in other groups. The rats in the latter 3 groups were inflicted with 40% TBSA full-thickness burns, and those in burn and SB203580, burn and isotonic saline groups were administered with SB203580 (p38 MAPK inhibitor) or isotonic saline, respectively. The levels of cPLA2 mRNA and membrane phospholipids in myocardium were detected with RT-PCR. In the same experiment, the effect of SB203580 on cPLA2 expression in rat myocardial cells was determined after hypoxia and burn serum treatment in vitro.


RESULTS
The level of myocardial cPLA2 mRNA in burn group at each time-point was obviously higher than those in normal group (0. 280 +/- 0. 020) , and it reached the peak value at 3 PBH. In contrast, the level of cardiac membrane phospholipids was lowered immediately after burns, and it reached the lowest level at 6 PBH [(0. 052 +/- 0. 017) mg phosphorus/mg protein]. Herein, a significant negative correlation was showed between the levels of cPLA2 mRNA and cardiac membrane phospholipids ( r = - 0. 53, P < 0. 05). Administration of SB203580, however, inhibited the increased activity of p38 MAP kinase, suppressed the upregulation of cPLA2(72% and 51% of those in burn and saline group, P <0. 01) , and markedly increased the levels of membrane phospholipids in myocardium at 6 and 12 PBH. In addition, treatment of cardiac myocytes with SB203580 also abolished the upregulation of cPLA2 mRNA elicited by hypoxia and burn serum challenge.


CONCLUSIONS
p38 MAP kinase play an important role in the burn-induced degradation of cardiac membrane phospholipids in rat through the upregulation of myocardial expression of cPLA2 mRNA in the myocardial cells.
Zhang
Jia-ping
JP
State Key Laboratory of Trauma , Burns and Combined Injury , Institute of Burns , Southwest Hospital , Third Military Medical University , Chongqing 400038 , PR China.
Ying
Xi
X
Huang
Yue-sheng
YS
Dang
Yong-ming
YM
Zhang
Dong-xia
DX
Li
Xiao-dong
XD
D000818:Animals; D002056:Burns / Q000378:metabolism*; D004195:Disease Models, Animal; D032383:Myocytes, Cardiac / Q000378:metabolism*; D054467:Phospholipases A2 / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D010743:Phospholipids; D012333:RNA, Messenger; D048051:p38 Mitogen-Activated Protein Kinases; D054467:Phospholipases A2