Lj. Tong et al., GTP-binding protein mediated phospholipase A(2) activation in rat liver during the progression of sepsis, MOL C BIOCH, 189(1-2), 1998, pp. 55-61
Effects of GTP-binding proteins on the activation of secretory phospholipas
eA, (sPLA(2)) and cytosolic phospholipaseA, (cPLA(2)) in rat liver during t
wo different phases of sepsis were studied. Sepsis was induced by cecal lig
ation and puncture (CLP). Experiments were divided into three groups: contr
ol, early sepsis, and late sepsis. Early and late sepsis refers to those an
imals sacrificed at 9 and 18 h, respectively, after CLP. The results show t
hat in the absence of G-protein modulator, hepatic sPLA(2) and cPLA(2) acti
vities were activated by 40.8-46 and 91.6-105.8%, respectively, during earl
y and late phases of sepsis. GTP gamma S and fluoroaluminate (AlF4-) stimul
ated sPLA(2) and cPLA(2) activities within each experimental group, i.e., c
ontrol, early sepsis, and late sepsis. The GTP gamma S and AlF4--stimulated
sPLA(2) and cPLA(2) activities remained significantly elevated during earl
y phase (22.3-65.6% increase) and late phase (32.5-109.1% increase) of seps
is. Further analyses demonstrate that cholera toxin significantly stimulate
d sPLA(2) and cPLA(2) activities within each experimental group, and that t
he cholera toxin stimulated sPLA(2) and cPLA(2) activities remained signifi
cantly higher during early phase (23.5-37% increase) and late phase (56.7-7
0% increase) of sepsis. In contrast, pertussis toxin significantly inhibite
d sPLA(2) and cPLA(2) activities within each experimental group, and that t
he pertussis toxin-inhibited sPLA(2) and cPLA(2) activities remained signif
icantly higher in early septic (57-68.5% increase) and late septic (34.6-45
.5% increase) experiments. These data demonstrate that cholera toxin-sensit
ive Gas and pertussis toxin-sensitive G alpha i were both involved in the a
ctivation of sPLA(2) and cPLA(2) activities in rat liver during the progres
sion of sepsis.