AJP - Cell Physiology, Vol 236, Issue 5 221-C224, Copyright © 1979 by American Physiological Society
Inhibition of short-circuit current by triaminopyrimidine in isolated toad urinary bladder
D. D. Fanestil and D. A. Vaughn
The organic cation 2,4,6-triaminopyrimidine (TAP) produced inhibition of
short-circuit current (SCC) when added to either the mucosal or serosal
surface of the isolated urinary bladder of the toad. Fifty percent
inhibition was produced by 10(-3) M TAP in the mucosal solution at pH 6.8
when the mucosal [Na+] was 113 mM. The actions of TAP resemble those
produced by amiloride in several ways: a) inhibition of SCC by mucosal
application is rapid; b) the mucosal inhibition is fully reversible; c)
high concentrations in the serosal solutions produce irreversible
inhibition; and d) the concentration required to produce 50% inhibition
from the mucosal side is reduced when mucosal [Na+] is reduced. It is
postulated that mucosal application of TAP and amiloride inhibit
short-circuit current in high-resistance epithelia via action at a common
locus.
