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Muscarinic and purinergic Ca 2+ mobilizations in the neural retina of early embryonic chick
Author(s) -
Sakaki Yoko,
Fukuda Yutaka,
Yamashita Masayuki
Publication year - 1996
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/s0736-5748(96)00074-3
Subject(s) - muscarinic acetylcholine receptor , purinergic receptor , muscarinic agonist , endocrinology , medicine , pertussis toxin , thapsigargin , phospholipase c , biology , carbachol , acetylcholine , oxotremorine , chemistry , microbiology and biotechnology , adenosine , intracellular , g protein , signal transduction , receptor , stimulation
Acetylcholine and adenosine triphosphate (ATP) raise intracellular Ca 2+ concentration via muscarinic receptors and P 2U purinoceptors by releasing Ca 2+ from intracellular Ca 2+ stores in the neural retina of early embryonic chick. The signal transduction mechanisms for the muscarinic and purinergic Ca 2+ responses with fura‐2 fluorescence measurements were studied. Li + (1 mM), which inhibits phosphatidylinositol metabolism, enhanced both the Ca 2+ rises to carbamylcholine (CCh, 30 μM), a muscarinic agonist, and ATP (200 μM). Thapsigargin (250 nM), an inhibitor of Ca 2+ ‐ATPase of inositol trisphosphate (IP 3 )‐sensitive Ca 2+ stores, abolished both the Ca 2+ rises to CCh (100 μM) and ATP (500 μM). U‐73122 (2 μM), an inhibitor of phospholipase C b , suppressed the Ca 2+ rise to ATP (500 μM), but its analog U‐73343 (2 μM) did not suppress it. In contrast, both U‐73122 and U‐73343 suppressed the Ca 2+ rise to CCh (100 μM). Pertussis toxin (250 ng/ml) suppressed the ATP‐induced Ca 2+ rise at least partly, whereas no inhibition was observed on the CCh‐induced Ca 2+ rise. Cross‐talk occurred between the muscarinic and purinergic Ca 2+ mobilizations but they were not occlusive. This study suggests that the muscarinic and purinergic Ca 2+ mobilizations utilize IP 3 ‐sensitive Ca 2+ stores, but different signal transduction pathways are involved in between the muscarinic and purinergic Ca 2+ responses.