AJP - Renal Physiology, Vol 250, Issue 3 503-F510, Copyright © 1986 by American Physiological Society
Effects of ouabain, amiloride, monensin, and other agents on ovine parotid secretion
R. D. Wright, J. R. Blair-West and J. F. Nelson
Secretion by the parotid gland of Na-replete and -depleted sheep was
investigated by examining the effects of modifiers of ionic transfer on
salivary composition and flow rate. These agents were infused into the
arterial blood supply of the vascularly isolated gland in anesthetized
sheep. Ouabain inhibited Na+-K+ exchange in the ducts caused by Na
depletion and restored the [Na+], [K+], and osmolality to close to those of
Na-replete saliva. Ouabain also inhibited Cl- -HCO3- exchange in the ducts
in Na repletion and depletion. Amiloride partially inhibited Na+-K+
exchange in Na depletion without affecting Cl- -HCO3- exchange. Monensin
potentiated Na+-K+ exchange in Na repletion and depletion. Amiloride and
monensin gained access to the saliva, but furosemide and ethacrynic acid
were almost totally excluded, and, up to 10(-3) M in blood, they did not
affect salivary composition or flow rate. Methazolamide gained free access
to saliva but was without effect.
4-Acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid at 10(-3) M
slightly increased salivary [Na+] and [HPO4(2-)]. The results indicate
potent effects of ouabain on basolateral Na+-K+ pumps and of amiloride and
monensin on transcellular delivery of Na+ to these pumps, but ouabain had
no effect on salivary flow rate until O2 consumption approached zero and
secretion failed. The findings do not support a proposal that the salivary
secretion depends on a Cl- -dependent furosemide-sensitive system energized
by Na+-K+-ATPase-dependent Na pumps.
