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Calcium waves along arteriolar endothelium enhance conducted vasodilation during blood flow control
Author(s) -
Segal Steven S.,
Brekke Johan F.,
Shui Bo,
Doran Robert M.,
Tallini N. Yvonne,
Kotlikoff Michael I.
Publication year - 2008
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.22.1_supplement.1141.7
Subject(s) - cremaster muscle , arteriole , vasodilation , chemistry , calcium , acetylcholine , microcirculation , anatomy , endothelium , biophysics , medicine , endocrinology , biology , organic chemistry
Conducted vasodilation (CVD) integrates electrical and chemical signals to coordinate smooth muscle relaxation along arterioles. In vitro studies suggest that acetylcholine (ACh) initiates both signals through a local increase in endothelial cell calcium (EC Ca 2+ ). To determine whether EC Ca 2+ increases along arterioles during CVD in vivo , we studied transgenic Cx40 BAC ‐GCaMP2 mice with the Ca 2+ sensor GCaMP2 expressed under the regulatory control of endogenous connexin40 (Cx40). Immunostaining confirmed selective coexpression of GCaMP2 and Cx40 in arteriolar EC. In the cremaster muscle of anesthetized males (9–16 wk; n =14), Ach microiontophoresis (1 μm tip, 1 μA, 1s) onto an arteriole [diameter (D)=30±2 μm; n=33] triggered a rapid rise in fluorescence at the stimulus site (t 1/2 =250±31 ms, ΔF/Fo=0.39±0.04; n=10). The EC Ca 2+ signal propagated bidirectionally at 116±6 μm/s, decaying by 50% in 204±17 μm with oscillations up to ∼1 mm away. Dilations were biphasic: ‘Rapid’ (>2 mm/s) CVD (ΔD=10–15 μm) occurred along several mm without remote changes in EC Ca 2+ and additional ‘slow’ CVD (ΔD=3–5 μm) occurred in the wake of an EC Ca 2+ wave. These respective signaling pathways effectively coordinate the onset, magnitude and duration of arteriolar dilations during the local control of tissue blood flow. (Support: NIH HL41026, HL56786, HL45239, DK65992 & F2HL76999).