Published in:
01-04-2007 | Experimental
Adrenomedullin reduces vascular hyperpermeability and improves survival in rat septic shock
Published in: Intensive Care Medicine | Issue 4/2007
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Objective
Current therapies of sepsis and septic shock require administration of a large volume of fluid to maintain hemodynamic stability. The vasoregulatory peptide adrenomedullin has been shown to prevent the transition to the fatal hypocirculatory septic state by poorly understood mechanisms. We tested the hypothesis that therapeutic administration of adrenomedullin would reduce vascular hyperpermeability, thereby contributing to improved hemodynamics and survival.
Design
Prospective randomized controlled animal study.
Subjects
Male Sprague–Dawley rats (270 g).
Interventions
We used 4.8 × 103 U/kg of Staphylococcus aureus α-toxin, a pore-forming exotoxin, to induce vascular leakage and circulatory shock in rats. The infusion rate was 24 μg/kg per hour. Adrenomedullin was started 1 h after α-toxin administration.
Measurement and results
Infusion of α-toxin in rats induced cardiocirculatory failure resulting in a 6-h mortality of 53%. α-Toxin provoked massive vascular hyperpermeability, which was indicated by an enrichment of Evans blue dye albumin in the tissues of lung, liver, ileum and kidney. Plasma fluid loss led to a significant hemoconcentration. Hemodynamic impairment observed after α-toxin infusion was closely correlated to vascular hyperpermeability. Therapeutic administration of 24 μg/kg per hour adrenomedullin reduced 6-h mortality from 53% to 7%. Stabilization of the endothelial barrier by adrenomedullin was indicated by reduced extravasation of albumin and plasma fluid and may have contributed to hemodynamic improvement.
Conclusions
These data suggest that adrenomedullin-related reduction of vascular hyperpermeability might represent a novel and important mechanism contributing to the beneficial effects of this endogenous vasoregulatory peptide in sepsis and septic shock.