Distribution of urea, thiourea-C14 and sucrose-C14 in dog kidney during antidiuresis

Abstract

The distribution of urea, thiourea-C¹⁴ and sucrose-C¹⁴ in the kidney and urine during antidiuresis has been investigated. An inverse relationship between the urine to papilla ratio and the papilla to cortex ratio for these three compounds has been demonstrated. For urea, the urine to papilla ratio is only 1.5, while the urea concentration in the papilla is 14 or more times that in the cortex. Studies with sucrose-C¹⁴ showed a urine to papilla ratio of 20 or more while the papilla sucrose-C¹⁴ concentration was only three to four times as high as the cortex. Thiourea-C¹⁴ behaved in a manner similar to urea, with high concentrations of isotope in the papilla and a urine to papilla ratio of 9. These results have been discussed in terms of the permeability of the collecting duct and the countercurrent exchanger function of medullary blood flow.