Functional expression of the adenosine A1 receptor in rabbit lacrimal gland.

It has become increasingly clear that purine compounds play a mediator role in exocrine secretion. Therefore, the present study was aimed at examining the presence of the adenosine A1 receptor in rabbit lacrimal gland and to evaluate the role of the A1 receptor in regulated secretion. The expression of the A1 receptor was investigated with reverse transcriptase PCR, cyto- and histochemistry as well as with pharmacological methods.

Characterization of beta-hexosaminidase secretion in rabbit lacrimal gland.

The present study was aimed at validating the use of the lysosomal enzyme beta-hexosaminidase as a marker of secretory function in cultured rabbit lacrimal gland acinar cells. The secretory response and morphological characteristics of isolated acinar cells cultured in a serum-free medium supplemented with an extracellular matrix extract were monitored over time as part of optimization of our culturing protocol. Secreted beta-hexosaminidase activity was analyzed and compared with that of another lysosomal enzyme, cathepsin B, as well as protein secreted into the media, w or w/o the presence of secretagogues or protein kinase C activators and inhibitors.

Integrin adhesion in regulation of lacrimal gland acinar cell secretion.

The extracellular microenvironment regulates lacrimal gland acinar cell secretion. Culturing isolated rabbit lacrimal gland acinar cells on different extracellular matrix proteins revealed that laminin enhances carbachol-stimulated secretion to a greater extent than other extracellular matrix proteins investigated. Furthermore, immunofluorescence indicated that integrin subunits, potentially functioning as laminin receptors are present in acinar cells.

Sequencing, expression, and enzymatic characterization of beta-hexosaminidase in rabbit lacrimal gland and primary cultured acinar cells.

The lysosomal enzyme, beta-hexosaminidase, exists as two major isoforms; HexA and HexB. HexA is an alpha beta-subunit heterodimer and HexB a beta-subunit homodimer. Both isoforms can remove nonreducing beta-N-acetyl-D-glucosamine residues, whereas HexA hydrolyzes charged substrates as G(M2) gangliosides as well.