LAUSR

What We Already Know about This TopicThe physiologic role of natriuretic peptides is increasingly understood in critical illness, but how these peptides might impact sepsis-induced oliguria is not known What This Article Tells Us That Is NewIn an in vivo study of experimental sepsis, fluid resuscitation restored glomerular filtration, but recombinant atrial natriuretic peptide restored renal tubular flow and glomerular filtration Background: Natriuretic peptides are used, based on empirical observations, in intensive care units as antioliguric treatments. We hypothesized that natriuretic peptides prevent lipopolysaccharide-induced oliguria by activating guanylyl cyclase A, a receptor for natriuretic peptides, in proximal tubules and endothelial cells. Methods: Normal Sprague-Dawley rats and mice lacking guanylyl cyclase A in either endothelial cells or proximal tubular cells were challenged with lipopolysaccharide and assessed for oliguria and intratubular flow rate by intravital imaging with multiphoton microscopy. Results: Recombinant atrial natriuretic peptide efficiently improved urine volume without changing blood pressure after lipopolysaccharide challenge in rats (urine volume at 4 h, lipopolysaccharide: 0.6 ± 0.3 ml · kg−1 · h−1; lipopolysaccharide + fluid resuscitation: 4.6 ± 2.0 ml · kg−1 · h−1; lipopolysaccharide + fluid resuscitation + atrial natriuretic peptide: 9.0 ± 4.8 ml · kg−1 · h−1; mean ± SD; n = 5 per group). Lipopolysaccharide decreased glomerular filtration rate and slowed intraproximal tubular flow rate, as measured by in vivo imaging. Fluid resuscitation restored glomerular filtration rate but not tubular flow rate. Adding atrial natriuretic peptide to fluid resuscitation improved both glomerular filtration rate and tubular flow rate. Mice lacking guanylyl cyclase A in either proximal tubules or endothelium demonstrated less improvement of tubular flow rate when treated with atrial natriuretic peptide, compared with control mice. Deletion of endothelial, but not proximal tubular, guanylyl cyclase A augmented the reduction of glomerular filtration rate by lipopolysaccharide. Conclusions: Both endogenous and exogenous natriuretic peptides prevent lipopolysaccharide-induced oliguria by activating guanylyl cyclase A in proximal tubules and endothelial cells.