Transport systems in human labial acinar cells.
Paulais, Marc, Ingrid H. Valdez, Philip C. Fox, Richard L. Evans, and
R. James Turner.
Clinical Investigations and Patient Care Branch, National Institute
of Dental Research, National Institutes of Health, Bethesda, Maryland
20892, USA
APStracts 2:0153G, 1995.
Human labial acini were assayed for the presence of ion transport
systems associated with salivary fluid secretion using
microfluorometric methods. Na+-K+-Cl_ cotransport and Na+/H+ exchange
activities (determined by their bumetanide and amiloride
sensitivities, respectively) were found at levels _50% of those seen
in similarly assayed rat parotid acini, but little, if any, Cl_/HCO3_
exchange activity was observed. Also, when human labial acini were
stimulated with the muscarinic agonist carbachol, little evidence of
the intracellular acidification associated with HCO3_ secretion by
other salivary glands was found. Na+/H+ exchange activity in human
labial acini was down-regulated (_40%) by [beta]-adrenergic
stimulation and up-regulated (_3-fold) by muscarinic stimulation. In
contrast, [beta]-adrenergic stimulation produced only a marginally
significant increase in Na+-K+-Cl_ cotransport activity and
muscarinic stimulation was without effect. We conclude that
basolateral Na+-K+-Cl_ cotransport appears to be the dominant
mechanism driving Cl_ secretion and thereby fluid secretion in this
tissue.
Received 24 February 1995; accepted in final form 25 July 1995.
APS Manuscript Number G83-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 August 1995.