Objective: To explore changes in endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP) in the myocardium after severe burn and delayed fluid resuscitation in rats at different altitudes.
Methods: Two hundred and forty male Wistar rats were employed as the experimental models with full-thickness burn of 30% total body surface area (TBSA), and they were randomly divided into three groups: delayed fluid resuscitation group (DFR), immediate fluid resuscitation group (IFR) and control group (CG). Samples of myocardial tissue were harvested at 1 hour, 6 hours, 12 hours, 24 hours, 72 hours, 168 hours postburn respectively. The changes in ET-1 and CGRP contents were determined by means of radio immunological assay.
Results: (1)The contents of ET-1 and CGRP in DFR group tended to increase at 6 hours after burn, ET-1 was higher 2.8, 3.6 fold, while CGRP higher by 2.2, 1.5 fold (P<0.01), compared with that of CG respectively at 1517 m and 3840 m. The tendency of rise of ET-1 and CGRP was significantly less conspicuous in IFR group than that in DFR group. (2)The contents of ET-1 in DFR group tended to increase at 6 hours and reached the peak at 24 hours after burn at 1517 m, while the levels reached the peak at 72 hours after burn at 3840 m, and the change lasted for 168 hours in DFR group. The contents of CGRP increased significantly at 6 hours and reached the peak at 12 hours at 1517 m, while they reached the peak at 72 hours after burn at 3840 m.
Conclusion: The myocardial contents of ET-1 tend to increase significantly with the elevation of altitude after severe burn in rats, but the contents of CGRP increased lagged behind. The result show that the higher the altitude is, the more the exhaustion of protective agents of the myocardium, thus resulting in changes in ET-1/CGRP.