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Endogenous Acetylcholine Detected by Changes in [Ca 2+ ] i Within Isolated Endothelial Cell Tubes
Author(s) -
Davis Harrison,
Bagher Pooneh,
Dora Kim,
Garland Christopher
Publication year - 2015
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.29.1_supplement.793.3
Subject(s) - acetylcholine , muscarinic acetylcholine receptor , atropine , endogeny , medicine , endocrinology , vasodilation , stimulation , receptor , chemistry , endothelium , paracrine signalling , muscarinic acetylcholine receptor m3 , blood vessel , biology
Stimulation of muscarinic acetylcholine (ACh) receptors expressed on the surface of endothelial cells (ECs) provides a powerful vasodilator response. However, these cells are not directly innervated, so it is unknown where endogenous ACh originates to activate the receptors. There is a considerable body of evidence to suggest that ACh can originate from non‐neuronal sources, so we investigated the possibility that blood cells may provide or stimulate the production of ACh. To assess the potential source of ACh, we freshly prepared EC tubes from isolated rat mesenteric arteries and measured [Ca 2+ ] i changes reported with Oregon Green ® 488 BAPTA‐1. To characterize this newly developed model, exogenous ACh was added and reproducibly stimulated asynchronous Ca 2+ waves that propagated through the cytoplasm in >95% of ECs. Application of rat whole blood to the EC tubes initiated a transient but robust increase in the frequency of EC Ca 2+ events (from 1.27 ± 0.19 basally to 5.18 ± 0.37 events.min ‐1 ) and the number of responsive cells (from 24 to 85%). In addition to blocking the response to exogenous ACh, the response to whole blood was significantly attenuated by the muscarinic receptor antagonist atropine (from 1.19 ± 0.17 basally to 2.54 ± 0.24 events.min ‐1 ). This suggests that the increase in EC Ca 2+ to whole blood is at least partly mediated by ACh, which provides a significant non‐neuronal auto or paracrine role for ACh on vascular tone. This work was supported by the British Heart Foundation.