OBJECTIVETo explore whether endothelin-1 and NO are involved in the instant changes in cardiac function at early stage of severe burn.

METHODS(1) Thirty-one Wistar rats were divided into sham burn A group (SA, n = 7), burn A group (BA, n = 10), non-selective endothelin A/B receptor antagonist PD142893 group (n = 7), and the selective endothelin A receptor antagonist BQ-123 group (n = 7) according to the random number table. Rats in the latter three groups were inflicted with 30% TBSA full-thickness burn. Immediately after injury, rats in PD142893 group and BQ-123 group were intravenously injected with PD142893 (0.1 mg/kg) and BQ-123 (30 nmol x kg(-1) x min(-1)) respectively. Rats in SA group were treated the same as rats in BA group except for sham injury. The cardiac function indexes of rats in BA and SA groups including left ventricular systolic pressure (LVSP) heart rate (HR) and LV + or - dp/dt max were monitored before injury and 10, 30, 60, 180 minutes post injury (PIM) using physiological signal acquisition and processing system. The respective changes in cardiac function indexes of rate in each group between PIM 10 and pre-injury in the value of percentage were calculated. (2) Another 20 Wistar rats were enrolled and divided into sham burn B group (SB, n = 4) and burn B group (BB, n = 16) according to the random number table, and they were subjected to above-mentioned injury. Heart tissues of rats in BB group were obtained at PIM 10, 30, 60, and 180 respectively (4 rats at each time point), and that in SB group were obtained immediately after injury. Endothelin-1 and NO contents in heart tissues were determined with ELISA.

RESULTS(1) Compared with the pre-injury value, LVSP, HR, LV +dp/dt max, LV -dp/dt max of rats in BA group decreased significantly since PIM 10 (with F value respectively 7.14, 16.40, 14.09 14.98, P < 0.05 or P < 0.01). No significant change was observed in above 4 indexes in rats of SB group between above mentioned two time points (with F value respectively 0.59, 0.51, 1.03, 1.04, P values all above 0.05). (2) In BA group, compared with the pre-injury value, LVSP decreased 27%, HR decreased 14%, LV +dp/dt max decreased 51%, LV -dp/dt max decreased 50% at PIM 10. Compared with those in BA group at PIM 10, cardiac function indexes were improved significantly in PD142893 group, with LVSP decreased 14% (F = 8.10, P < 0.01), HR increased 4% (F = 6.50, P < 0.01), LV +dp/dt max decreased 31% (F = 23.67, P < 0.05), LV -dp/dt max decreased 14% (F = 10.39, P < 0.01). In BQ-123 group, compared with the pre-injury value, HR increased 3%, LV -dp/dt max decreased 26% at PIM 10, which were obviously improved as compared with those in BA group (with F value respectively 6.50 and 10.39, P < 0.05 or P < 0.01); the percentage changes of LVSP and LV +dp/dt max in BQ-123 group were close to that in BA group (with F value respectively 8.10 and 23.67, P values both above 0.05). (3) Compared with those in SB group, myocardial tissue endothelin-1 content of rats in BB group increased significantly at PIM 10, 60, 180 (F = 2.85, P < 00.05 or P < 0.01), and NO content increased significantly at PIM 60, 180 (F = 1.87, with P values all below 0.05).

CONCLUSIONSEndothelin-1 may participate in the instant decline of cardiac function of rats at early stage of severe burn, and plays an important role in the instant myocardial damage after injury.