AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 1 45-R52, Copyright © 1983 by American Physiological Society
Control of ion transport by Gillichthys mirabilis urinary bladder
C. A. Loretz and H. A. Bern
The columnar epithelial cell region of the goby Gillichthys mirabilis
urinary bladder is the region responsible for active Na and Cl reabsorption
from bladder urine. In 5% seawater-adapted fish, reabsorption occurs via an
electrically silent coupled NaCl transport mechanism. Bladder reabsorption
is increased in seawater-adapted fish above that observed in 5%
seawater-adapted fish; incremental reabsorption results from an
electrogenic Na transport in addition to the neutral component.
Hypophysectomy of seawater-adapted fish reduces the electrogenic Na
transport (measured as short-circuit current, ISC) and increases the
transepithelial resistance (R) to values near those of 5% seawater-adapted
fish. Cortisol restores the ISC and R to normal seawater-adapted values and
will initiate electrogenic Na transport in 5% seawater-adapted fish. Ovine
prolactin will also restore the ISC and R of columnar cell regions of
hypophysectomized seawater-adapted fish to normal seawater-adapted levels;
this effect appears to be due to contamination or to inherent stimulatory
activity of the ovine prolactin preparation, since endogenous prolactin is
ineffective in the restoration of ISC or R.
