Bohdan R. Nechay

Handling of urine by cloaca and ureter in chickens

Abstract 1. 1. The contribution of the cloaca to salt and water transfer was studied by comparison of urine collected directly from one kidney with urine collected simultaneously from the other kidney after passage through the ureter and cloaca. 2. 2. The only process observed in the cloaca-ureter area was passive absorption of water from urine hypotonic to plasma. 3. 3. Within the limits of the method no movements of ions against the concentration gradient occurred. 4. 4. The cloaca appears to have no active role in salt and water transport in chickens. 5. 5. Mannitol reduced glomerular filtration rate and salt and water output by the kidney connected to the cloaca by the ureter as opposed to osmotic diuresis induced in the cannulated kidney.

Effect of ouabain on renal transport of P-aminohippuric acid (PAH) and blood flow in the dog☆

Abstract PAH was infused i.v. to establish plasma concentrations of 2 to 48 mg%. Ouabain was given into one renal artery at rates of 0.7 to 1.3 μg/kg/min for 60 to 80 min. In most experiments there was a clear dissociation between the effects of ouabain on PAH and Na + transport indicating a certain selectivity for the cation. At plasma PAH concentration of 2 mg% ouabain initially reduced ipsilateral tubular extraction of PAH and renal blood flow. Both values returned promptly to control levels when a large ipsilateral inhibition of Na + reabsorption occurred. At plasma PAH concentration of 30 to 48 mg% the early response to ouabain was characterized by a depression of ipsilateral tubular maximal transport capacity for PAH and a beginning natriuresis, the late effect by a persistent depression of Na + reabsorption and a gradual return of PAH secretion rate to the levels of the opposite (control) kidney. Either the mechanisms of PAH and Na + inhibition by ouabain are different or the dissociation of ouabain effects on PAH and Na + transport is the result of intrarenal distribution of the drug.