AJP - Renal Physiology, Vol 242, Issue 5 453-F456, Copyright © 1982 by American Physiological Society
Effect of adrenal enucleation on inner medullary collecting duct function in the rat
H. H. Bengele and E. A. Alexander
After adrenal enucleation rats have an impaired ability to excrete a salt
load. From micropuncture studies comparing data obtained from the late
distal collection site and the urine, it has been suggested that this
antinatriuretic effect occurs along the collecting duct. These studies are
indirect, however, and cannot evaluate the contribution of deep nephrons.
We have performed studies directly measuring inner medullary collecting
duct (IMCD) function in saline-loaded rats 6 days after adrenal enucleation
(AE). The fraction of filtered fluid, sodium, chloride, and potassium was
analyzed as a function of IMCD length. In six AE rats 35% of the fluid, 35%
of the sodium, and 31% of the chloride delivered to the IMCD was
reabsorbed. In six saline-loaded control rats, however, no statistically
significant net reabsorption of fluid sodium, or chloride was detected. Net
potassium secretion along the IMCD was found in both AE and control rats.
No difference between groups was noted, and net addition accounted for 17%
of the potassium excreted. We conclude that after AE, the excretion of
fluid, sodium, and chloride is impaired during saline expansion because of
enhanced reabsorption along the IMCD. AE does not affect potassium handling
along the IMCD or potassium excretion.
