Methylene blue reverses endotoxin-induced hypotension

Abstract

Hypotension in septic shock is a reflection of unregulated nitric oxide (NO) production and vascular smooth muscle guanylyl cyclase activation. We examined the effect of methylene blue on lipopolysaccharide (LPS)-induced shock in anesthetized rabbits. Shock was induced with 150 μg/kg LPS after measurement of mean arterial pressure, platelet cGMP, and total plasma NO (nitrogen monoxide + S-nitrosothiol) content. Measurements were repeated before and after the intravenous administration of 1, 5, and 10 mg/kg methylene blue in response to a 55% reduction in mean arterial pressure. At baseline, mean±SEM arterial pressure was 88±3 mm Hg, which fell to 51±3 mm Hg after LPS (P