Conclusions
P2X(7) purinergic receptors are present in rat lacrimal gland and when stimulated increase [Ca(2+)](i), protein secretion, and ERK 1/2 activation.
Methods
P2X(7) purinergic receptors were identified by RT-PCR, Western blot analysis, and immunofluorescence techniques. Rat lacrimal gland acini were isolated by collagenase digestion. Acini were incubated with the fluorescent indicator molecule fura 2, and [Ca(2+)](i) was measured by a fluorescence imaging system. Protein secretion was measured with a fluorescence assay system. Activation of ERK 1/2 was determined by Western blot analysis with an antibody against phosphorylated (active) ERK 1/2.
Purpose
To characterize the effects of P2X(7) purinergic receptors on lacrimal gland function.
Results
P2X(7) receptors were present in the lacrimal gland by RT-PCR and Western blot analysis. These receptors were located in the membranes of acinar and ductal cells and the cytoplasm of acinar cells. Activation of P2X(7) receptors with (benzoylbenzoyl)adenosine 5'-triphosphate increased [Ca(2+)](i), peroxidase secretion, and ERK 1/2 activation, each of which was inhibited by the P2X(7) receptor inhibitors Brilliant Blue G or A 438079. Conclusions: P2X(7) purinergic receptors are present in rat lacrimal gland and when stimulated increase [Ca(2+)](i), protein secretion, and ERK 1/2 activation.