Abstract: AIM:To investigate the protective effects of a delta opioid receptor agonist, [ D-Ala(2), DLeu(5) ]-enkephalin (DADLE), on cultured myocardial cells with hypoxia/reoxygenation (H/R) injury. METHODS:The H/R injury model of cultured myocardial cells was made by SD suckling mice. The cell shape, livability, the activity of lactate dehdrogenase (LDH) and superoxide dismutase (SOD), and the content of malondialdehyde (MDA) of the cultured myocardial cells injured by H/R were determined. RESULTS:Compared with normal group, the cell livability and the SOD activity of model group after reoxygenation 30 min were decreased respectively, whereas the activity of LDH and the content of MDA of model group were increased significantly (P <0.01). Every index in the model group was changed to normal degree after reoxygenation for 60 min. In myocardial cells injured by H/R which were treated with 1 μmol/L DADLE, the LDH release and MDA content were decreased, while the cell livability and SOD activity were enhanced (P <0.01). A selective delta opioid receptor antagonist, naltrindole, at 10 μmol/L antagonized the effects of DADLE. CONCLUSION:DADLE has protective effects on the cultured myocardial cells injured by H/R by the stimulation of delta opioid receptor.

Key words: delta opioid receptor, myocardial cell, hypoxia reoxygenation injury