AJP - Gastrointestinal and Liver Physiology, Vol 239, Issue 3 183-G189, Copyright © 1980 by American Physiological Society
Effects of carbachol on extracellular Na-dependent AIB uptake in rat parotid gland
G. Keryer and B. Rossignol
In rat parotid glands the uptake of 2-[1-14C]aminoisobutyric acid (AIB), in
vitro, depends on a Na concentration gradient between the intra- and
extracellular medium. Ouabain (1 mM) which inhibits the Na+-K+-ATPase and a
Na+ ionophore, monensin (which dissipates the Na+ gradient), both suppress
this amino acid uptake. Carbachol (5 microM) (through muscarinic receptors)
evokes a decrease in AIB uptake, and in the presence of 0.1 mM ouabain the
cholinergic effect is enhanced. Ouabain alone (0.1 mM) very slightly
depresses the [14C]AIB uptake. Neither 1 microM isoproterenol, nor 1 microM
Ca2+ ionophore A23187, which affect the membrane potential in rat parotid
acinar cells, modifies the AIB uptake. When the Ca is removed from the
incubation medium, carbachol still evokes a small decreasing effect on AIB
uptake. From these data we can suggest that the reduced AIB uptake (induced
by the cholinergic agonist) appears to be related to a process dependent on
variation of intracellular Na concentration that may be triggered by the
cholinergic agonist.
