[Changes in cardiac renin-angiotensin system after severe burn injury in rats]

To observe changes in cardiac renin-angiotensin and its effect on sarcoplasmic reticulum(SR) calcium transport function, and investigate the mechanism underlying cardiac dysfunction in early postburn stage.

Rats were divided into three groups: control group (n = 8, without burns), burn group (n = 40, 30% TBSA full-thickness burns), and treatment group (n = 40, gavage Lisinopril for 3 days before 30% TBSA burns). The left ventricular(LV) contractile function was measured at 3, 8, 24 hours postburn. Angiotensin converting enzyme(ACE) activities, the contents of angiotensin II (AII) and calcium in myocardium were also measured. In addition, Ca(2+)-ATPase activities and calcium transport function in SR were determined.

The maximal rates of LV pressure rise (+/- dp/dtmax) and fall (-dp/dtmax) in burn group were significantly lower than that in control group. The ACE activities, AII levels, as well as calcium contents in myocardium increased markedly in burn group. Ca(2+)-ATPase activities and Ca2+ uptake function in SR decreased significantly in burn group. After treatment with ACE inhibitor-Lisinopril, the ACE activities, AII levels and calcium contents were significantly decreased compared to the burn group. Meanwhile, Ca(2+)-ATPase activities, calcium uptake function and LV contractile function decreased markedly.

The cardiac renin-angiotensin system is activated rapidly after severe burns and inhibits the calcium transport function which may play an important role in cardiac contractile dysfunction following burns.