Effect of Volume Expansion on Hemodynamics of the Hypoperfused Rat Kidney
AUTOR(ES)
Johnston, Paul A.
RESUMO
The hemodynamics of the rat kidney were studied during reduction of renal arterial pressure to 35-40 mm Hg (H), and after volume expansion at that pressure with 0.9% NaCl (IS), 1.7% NaCl (HS), 5% mannitol in 0.9% NaCl (MS), 5% mannitol in water (MW), or 50 mM mannitol + 125 mM NaCl. During H, left renal blood flow (RBF) was 0.8±0.1 ml/min. Expansion with IS did not alter RBF, but expansion with HS, MS, MW, and 50 + 125 mM NaCl elevated RBF to 200-250% of hypoperfusion values. Glomerular capillary pressure rose significantly from 15.7±0.7 mm Hg during H to 22.3±1.1, 24.4±0.7, and 26.6±0.7 mm Hg following expansion with HS, MS, or MW, respectively. Efferent arteriolar pressure also rose significantly to 6.9±0.5, 9.7±0.8, and 9.5±0.9 mm Hg, respectively. Preglomerular resistance fell to 18-24% of H values, and postglomerular resistance fell to 58-74% of H values after expansion with HS, MS, or MW. Glomerular filtration (GFR) could not be detected during H or after IS expansion. HS and mannitol-containing solutions restored GFR to 0.10±0.02-0.15±0.02 ml/min, and single nephron glomerular filtration to 6-12 nl/min. Papaverine, acetylcholine, and kinins had no effect on RBF or GFR at a perfusion pressure of 35-40 mm Hg. We conclude that mannitol and HS have the capacity to augment RBF during hypoperfusion by reducing arteriolar resistance. The mechanism of the rise in RBF is uncertain; it may be due to changes in effective osmolality of the extracellular fluid or to a direct action of mannitol on vascular smooth muscle. Other potent vasodilators were ineffective during hypoperfusion. Restoration of GFR occurs as a result of the combined effects of augmented RBF and elevated net filtration pressure.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=372150Documentos Relacionados
- Prostaglandins mediate the vasodilatory effect of mannitol in the hypoperfused rat kidney.
- Systemic and Renal Hemodynamics in Oliguric Hepatic Failure: Effect of Volume Expansion*
- Further Studies on Segmental Sodium Transport in the Rat Kidney during Expansion of the Extracellular Fluid Volume
- Effects of Acute Volume Expansion and Altered Hemodynamics on Renal Tubular Function in Chronic Caval Dogs
- Micropuncture Studies of Sodium Tranport in the Remnant Kidney of the Dog THE EFFECT OF GRADED VOLUME EXPANSION