Stimulation by P2X₇ receptors of calcium-dependent production of reactive oxygen species (ROS) in rat submandibular glands.
BACKGROUND
Agonists of P2X₇ receptors increase the production of reactive oxygen species (ROS) in immunocytes. In this work we tested this response and its effect on mitochondrial inner membrane potential (Deltapsi(m)) in exocrine glands.


METHODS
The production of ROS by rat submandibular glands was investigated by measuring the oxidation of dichlorodihydrofluorescein (DCFH), a fluorescent probe. The Deltapsi(m) was estimated with tetramethylrhodamine.


RESULTS
Activation of P2X₇ receptors by ATP or Bz-ATP increased the production of ROS. This response was not modified by inhibitors of phospholipase A2 or of various kinases. The effect of ATP was calcium-dependent and was blocked by diphenyliodonium, an inhibitor of flavoproteins. It was not affected by rotenone, an inhibitor of the complex I of the mitochondrial electron transfer chain. Scavengers of ROS had no effect on the dissipation of Deltaψ(m) by ATP.


CONCLUSIONS
We conclude that, in rat submandibular glands, P2X₇ receptors stimulate in a calcium-dependent manner an oxidase generating ROS, suggesting the involvement of the dual oxidase Duox2. The production of ROS does not contribute to the depolarization of mitochondria by purinergic agonists.


CONCLUSIONS
Purinergic receptors could be regulators of the bactericidal properties of saliva by promoting both the secretion of peroxidase from acinar cells and by activating Duox2.
Fontanils
U
U
Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias, Universidad del Pais Vasco, 48080 Bilbao, Spain.
Seil
M
M
Pochet
S
S
El Ouaaliti
M
M
Garcia-Marcos
M
M
Dehaye
J P
JP
Marino
A
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004579:Electron Transport; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D013363:Submandibular Gland / Q000166:cytology / Q000378:metabolism*
C546470:P2rx7 protein, rat; D017382:Reactive Oxygen Species; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D002118:Calcium