Ion transport systems in human labial acinar cells.
Human labial acini were assayed for the presence of ion transport systems associated with salivary fluid secretion using microfluorometric methods. Na(+)-K(+)-Cl- contransport and Na+/H+ exchange activities (determined by their bumetanide and amiloride sensitivities, respectively) were found at levels approximately 50% of those seen in similarly assayed rat parotid acini, but little, if any, C1-/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 downregulated (approximately 40%) by beta-adrenergic stimulation and upregulated (approximately threefold) 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 include that basolateral Na(+)-K(+)-Cl- cotransport appears to be the dominant mechanism driving Cl- secretion and thereby fluid secretion in this tissue.
Paulais
M
M
Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
Valdez
I H
IH
Fox
P C
PC
Evans
R L
RL
Turner
R J
RJ
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D000818:Animals; D017920:Antiporters / Q000378:metabolism*; D001692:Biological Transport; D002217:Carbachol / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D027963:Chloride-Bicarbonate Antiporters; D018678:Cholinergic Agents / Q000494:pharmacology; D005260:Female; D006801:Humans; D007477:Ions; D007545:Isoproterenol / Q000494:pharmacology; D008046:Lip; D008297:Male; D008875:Middle Aged; D051381:Rats; D017208:Rats, Wistar; D012470:Salivary Glands, Minor / Q000166:cytology / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D028021:Sodium-Potassium-Chloride Symporters
D000318:Adrenergic beta-Agonists; D017920:Antiporters; D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D018678:Cholinergic Agents; D007477:Ions; D017923:Sodium-Hydrogen Exchangers; D028021:Sodium-Potassium-Chloride Symporters; D002217:Carbachol; D007545:Isoproterenol