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Signaling pathways underlying the P2Y 1 receptor‐mediated excitation of the preBötzinger Complex (preBötC) inspiratory rhythm generating network in vitro
Author(s) -
Rajani Vishaal,
Zwicker Jennifer D,
Panaitescu Bogdan,
Alvares Tucaaue S,
Chaves Elena Posse,
Ballanyi Klaus,
Funk Gregory D
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1088.7
Subject(s) - carbenoxolone , egta , purinergic receptor , intracellular , gap junction , medicine , endocrinology , p2y receptor , biophysics , thapsigargin , second messenger system , agonist , biology , chemistry , receptor , microbiology and biotechnology , calcium
The ventilatory response to hypoxia comprises an initial increase in ventilation followed by a secondary depression. The release of ATP within the respiratory network, including the preBötC, attenuates the depression, in part via a P2Y 1 receptor (R), preBötC mechanism involving neurons and glia. To characterize the signaling pathways underlying the P2Y 1 excitation, we used primary cultures of preBötC astrocytes loaded with Fluo‐4 and compared the fluorescence response evoked by ATP (10 μM) in control and after bath application of carbenoxolone (CBX, gap junction blocker 100 μM) and membrane permeant 2 nd messenger blockers. CBX had no effect but U73122 (phospholipase C antagonist) and thapsigargin (depletes intracellular Ca 2+ (Ca 2+ i ) stores) blocked ATP‐evoked Ca 2+ i increases. In rhythmic medullary slices from neonatal rat, CBX had no effect on the frequency (f) response evoked by ATP (100 μM, 10 sec) in the preBötC. To test the role of Ca 2+ i we compared the f response to MRS2365 (P2Y 1 R agonist, 100 μM) before and after application of EGTA‐AM (1 mM) into the preBötC. EGTA reduced the control, 2.2±0.3 fold MRS2365 f increase by 64±7%. Response duration fell to 35±6% of control. In cultured preBötC glia, ATP‐evoked Ca 2+ i increases reflect PLC‐induced release from intracellular stores. In the preBötC, increases in Ca 2+ i contribute to the P2Y 1 ‐evoked frequency increase. Supported by CIHR, WCHRI, AIHS & ALA.