Renal cortical blood flow and glomerular filtration in myohemoglobinuric acute renal failure

Renal cortical blood flow and glomerular filtration in myohemoglobinuric acute renal failure.Renal cortical blood flow measurements were made serially after the induction of myohemoglobinuric acute renal failure in water-drinking rats and others given 150 mM saline for a month in place of drinking water.Blood flow in both groups fell to some one-third of control in the first two hours after injection.Cortical perfusion of water drinking rats stabilized at approximately 24% of control for the 24 hour study period, but rose rapidly to 85% of control in the saline-drinking group.Glomerular filtration (GFR) of water-drinking animals was too slow for accurate measurement.GFR improved concomitantly with blood flow in the saline-drinking animals, reaching 84% of control within 12 hours.Estimations of intra-glomerular pressure at various blood flow rates and calculated pre- and postglomerular resistances suggested that filtration failure in water-drinking rats was primarily attributable to preglomerular vascular resistance change.A small decrease in postglomerular resistance could not be ruled out, however.In recovery, increased preglomerular resistance still was chiefly responsible for any residual deficit in glomerular filtration and cortical blood flow, but an inhomogeneity of nephron perfusion found earlier, and/or an element of postglomerular vascular relaxation, lowered filtration below that predicted on the basis of preglomerular constriction alone.Long-term saline loading prior to the induction of myohemoglobinuria appears to prevent acute renal failure by abolishing sustained renal cortical ischemia. Débit sanguin rénal cortical et filtration glomérulaire lors de l'insuffisance renale aigüe myohemoglobinurique.Chez deux groupes de rats en état d'insuffisance rénale aigüe induite par l'injection de glycérol, on a repété les mesures de débit sanguin du renal cortical et de filtration glomérulaire.Le premier groupe était soumis à un régime normosodé et le second à une charge sodée depuis un mois.Dans les deux groupes, le débit sanguin cortical, mesuré dans les deux heures suivant l'injection, est diminué de 1/3 par rapport aux valeurs témoins.Chez les rats en regime normosodé, les valeurs du débit cortical restent basses pendant les 24 heures d'étude, tandis qu'elles croissent jusqu'à 85% des valeurs témoins dans l'autre groupe.La valeur de la filtration glomérulaire chez les rats normosodes est trop basse pour être mesurée.Chez les animaux en régime hyperso