Objective To investigate the pulmonary water content and the mRNAs and the proteins levels of aquaporin-1 (AQP-1) of lung tissues of brain death rats and to investigate the effects of calcitonin gene-related peptide (CGRP) on the Changes of corresponding indicators of brain death rats.Methods 15 adult Wistar rats were randomly grouped into control (A),brain-death (B) and CGRP treatment (C).Brain-death model was established in group B and group C.The group A were placed Foley balloon catheter in intracalvarium only; no brain-death model established.In group C,CGRP 3 μg/kg was injected intravenously immediately after establishment of brain-death model,followed by 0.5 μg/(kg· h)CGRP administered 12 h.At 12 h after the initial brain death,lung tissues were taken,the lung index and lung water content were measured.Histological alterations in lung tissues were examined by hematoxylin and eosin (HE) staining.The levels of AQP-1 were tested by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blottng.Results In contrast to group A (4.12 ± 0.39,0.70 ± 0.08),lung index and lung water content were higher in group B (7.16 ± 0.58,0.91 ± 0.07) and C (5.28 ± 0.43,0.80 ± 0.05).In contrast to group B,lung index and lung water content were lower in group C (P <0.05).The lung injury was identified by HE staining in group B and C,though less pathologic alterations were shown in group C.The lung Histological examination in group A was normal.The mRNA level and the protein level of AQP-1 in group B (0.51 ± 0.05,0.32 ± 0.05)were lower than that in group A (0.76 ±0.03,0.49 ±0.04),while that in group C (0.98 ±0.04,0.53 ±0.02)were higher than that in group B(P < 0.05).Conclusion CGRP can increase the mRNA level and the protein level of AQP-1,reduce lung water content,and alleviate pulmonary edema in lung tissue of brain death rats. Key words: Brain death; Calcitonin gene-related peptide; Aquaporin-1 ; Lung water content