Effect of ureteral blockade on renal blood flow and urinary concentrating ability

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Abstract
Complete blockade of the ureter in dogs subjected to saline loading (0.85–10.0% NaCl) resulted in an increase in total renal blood during the period of blockade which appeared to be related to the antecedent diuresis and increment in ureteral pressure. This was accompanied by a progressive decrease in extraction of para-aminohippurate (PAH) and a greater decrease in creatinine extraction. The change in Epah showed a close inverse correlation to the change in renal blood flow (RBF). This afforded a possible explanation for the increment in RBF, for the increased perfusion of vascular circuits of the A-V communicating type would account for such a correlation. Evidence was supplied which suggested that such pathways involved the medullary vascular circuits. This was based on the observation that the concentrating ability of the kidney was impaired by the period of occlusion. The most likely mechanism for this would be maintained (or increased) vascular perfusion of the vasa recta system, in the face of markedly curtailed glomerular filtration, conditions resulting from ureteral blockade.