Acute effects of brief ureteral stasis on urinary and renal papillary chloride concentration

Abstract

According to the countercurrent hypothesis urine tonicity depends largely on osmotic equilibrium of collecting duct fluid with the hypertonic interstitium of the papilla. One suggested role of ADH is that of regulating water permeability of collecting duct epithelium. In water deprivation ADH would facilitate water movement from collecting duct to the hypertonic papilla. Support for this hypothesis is offered here. These studies use the observation that ureteral clamping curtails glomerular filtration. Hence, the filtered load of NaCl from which papillary stores are derived is reduced. Accordingly, the chloride content of papillary tissues obtained from dog kidneys subsequent to several minutes of ureteral clamping was compared to those from the opposite kidney. In saline-loaded animals stasis uniformly lowered tissue chloride with the production of urine lower in chloride content and hypotonic to that of the contralateral side. These alterations were minimized following urinary stasis in animals loaded with water, mannitol or saline plus ADH.