New experimental method to study acid/base transporters and their regulation in lacrimal gland ductal epithelia.
OBJECTIVE
The main function of the lacrimal gland is to produce the most aqueous component of the tear film covering the surfaces of the cornea and the conjunctiva. Studies have been conducted that characterize the mixed fluid and protein secretion of isolated acini, but no methods have been developed to characterize lacrimal gland ductal cell (LGDC) secretion. Secretory mechanisms of ductal epithelia may play physiological roles in the maintenance of the standard environments for the cornea and the conjunctiva.


METHODS
In this study, the authors developed a rapid method to isolate large quantities of intact lacrimal ducts. The preparation of isolated intact lacrimal gland ducts for the first time enabled the performance of real-time functional experiments on cleaned ducts. Electron microscopy and fluorescence measurements were used to evaluate the viability of lacrimal ducts.


RESULTS
Fluorescence measurements showed that LGDCs express functionally active Na(+)/H(+) exchanger (NHE) and Cl(-)/HCO(3)(-) exchanger (AE). Parasympathomimetic stimulation by carbachol stimulated NHE and AE through the elevation of intracellular calcium concentration. This mechanism can play a role in the regulation of ion and water secretion by LGDCs.


CONCLUSIONS
The authors have described a lacrimal gland duct isolation technique in which the intact ducts remain viable and the role of duct cells in tear film secretion can be characterized. These data combined with the novel isolation facilitated understanding of the regulation mechanisms of ductal cell secretion at cellular and molecular levels under normal and pathologic conditions.
Tóth-Molnár
Edit
E
Department of Ophthalmology, University of Szeged, Szeged, Hungary.
Venglovecz
Viktória
V
Ozsvári
Béla
B
Rakonczay
Zoltán
Z
Varró
András
A
Papp
Julius G
JG
Tóth
András
A
Lonovics
János
J
Takács
Tamás
T
Ignáth
Imre
I
Iványi
Béla
B
Hegyi
Péter
P
D000136:Acid-Base Equilibrium / Q000502:physiology*; D000143:Acids / Q000378:metabolism; D000468:Alkalies / Q000378:metabolism; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D007765:Lacrimal Apparatus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D046529:Microscopy, Electron, Transmission; D009924:Organ Culture Techniques / Q000379:methods*; D010277:Parasympathomimetics / Q000494:pharmacology; D011817:Rabbits; D027982:Sodium-Bicarbonate Symporters / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
D000143:Acids; D000468:Alkalies; D027963:Chloride-Bicarbonate Antiporters; D010277:Parasympathomimetics; D027982:Sodium-Bicarbonate Symporters; D017923:Sodium-Hydrogen Exchangers; D002217:Carbachol