Nonselective inhibition of nitric oxide (NO) with NO synthase antagonists decreases hypotension but worsens outcome clinically. We investigated whether iron (III) complex of diethylenetriaminepentaacetic acid [DTPA Fe(III)], a scavenger of NO as well as other oxidant mediators, has similar divergent effects in E. coli challenged rats.Methods:
Animals with venous and arterial catheters and challenged with intrabronchial or intravenous E. coli were randomized to treatment with DTPA Fe(III) in doses from 3 to 800 mg/kg or placebo. Mean blood pressure (MBP) was measured in all animals and plasma NO, cytokines, and blood and lung leukocyte and bacteria counts in animals administered intrabronchial E. coli and DTPA Fe(III) 50 mg/kg or placebo. Animals received antibiotics and were observed 168 h.Results:
Independent of drug regimen or infection site, compared to placebo, DTPA Fe(III) increased MBP although this was greater with high vs. lower doses. Despite increased MBP, DTPA Fe(III) worsened the hazards ratio of survival. At 6 and 24 h DTPA Fe(III) decreased NO but not significantly and decreased four cytokines (tumor necrosis factor-α, interleukins 1 and 10, and macrophage inflammatory protein 3α) and lung lavage neutrophils. From 6 to 24 h DTPA Fe(III) increased blood bacteria.Conclusions:
DTPA Fe(III) while increasing blood pressure has the potential to worsen outcome in sepsis. Further preclinical testing is required before this agent is applied clinically.