Abstract:

Objective    To investigate the effects of extraneous adrenomedullin(ADM) on Ang-Ⅱand MDA expression, and the protective action of ADM in early mechanical renal trauma.  Methods    104 healthy adult plain grade Wister rats were randomly divided into four groups: 8 in the control group, 32 in the trauma group,  32 in the group in which ADM was injected before trauma, and 32 in the group in which ADM was administered after the trauma. The model of mechanical kidney trauma was established by striking the skin area exactly above the kidney with a free falling ferrous hammer. In the latter two groups, ADM (0.1nmol/kg) was injected intraperitoneally 10 minutes before or after the striking. All rats were executed in batches at the 1st, 6th,12th, 24th hour after the trauma. The supernatant of renal homogenates was collected and the concentrations of Ang-II and MDA were detected by radioimmunoassay or colorimetry, respectively. Results     1) Concentration level of Ang-II: The concentration of Ang-II in the trauma group was significantly higher than that in the control group in the early trauma (1st, 6th hr) (P<0.05). Also, both the concentrations of Ang-II in the group injected with ADM before trauma (1st, 6th hr) and the group injected  with ADM 1hr after trauma at were lower than that in the trauma group (P<0.05). 2) Concentration level of MDA: The concentration of MDA in the trauma group was obviously higher than that in the control group at 1 h (P<0.05). But the concentrations of MDA either in the group injected with ADM 6 hrs before trauma or the group injected with ADM 12 hrs after trauma were lower than that in the trauma group (P<0.05). Conclusions     Extraneous ADM can exert a protective effect onrenal trauma by controlling the concentration of Ang-Ⅱand MDA. More importantly, ADM injected before trauma shows stronger effect on renal trauma than that injected after trauma.

Key words: Kidney; Trauma; Adrenomedullin; AngII; MDA