Phospholipase A2Activities Are Decreased during Early but Increased during Late Phases of Sepsis in Rat Heart

Abstract

Background.Changes in the activities of secretory phospholipase A2(sPLA2) and cytosolic phospholipase A2(cPLA2) in the rat heart during early hyperdynamic and late hypodynamic phases of sepsis were studied in an attempt to understand the pathophysiology of cardiac dysfunction during sepsis.Methods.Sepsis was induced by cecal ligation and puncture (CLP). Experiments were divided into three groups: control, early sepsis, and late sepsis. Early and late sepsis refers to those animals sacrificed at 9 and 18 h, respectively, after CLP. PLA2activity was measured based on the rate of hydrolysis of 1-palmitoyl-2-[1-14C]oleoyl phosphatidylcholine.Results.The results show that under physiological conditions, sPLA2and cPLA2activities were time and protein dependent. The optimal Ca2+concentrations for sPLA2and cPLA2activities were 3 mM and 40 μM, respectively. During sepsis, sPLA2activity was decreased by 25% (P< 0.01) during early phase while it was increased by 49% (P< 0.01) during late phase of sepsis. Similarly, cPLA2activity was decreased by 23% (P< 0.01) during early sepsis while it was increased by 60% (P< 0.01) during late sepsis.Conclusions.Since PLA2functions to maintain cell membrane integrity and function, a biphasic change in sPLA2and cPLA2activities may contribute to the development of the two cardiodynamically distinct phases during the progression of sepsis.