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Different Role of Calcium‐activated Potassium Channels in Human Internal Mammary (IMA) and Radial Artery (RA)
Author(s) -
Fan Li,
Xiao XiaoQiu,
Grove Kevin,
Yang Qin,
Furnary Anthony,
He GuoWei
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.1155.11
Subject(s) - apamin , charybdotoxin , chemistry , potassium channel , calcium activated potassium channel , iberiotoxin , acetylcholine , potassium , medicine , endocrinology , pharmacology , biophysics , biology , organic chemistry
We investigated the contribution of small (SKCa) and intermediate conductance calcium‐activated potassium channel (IKCa) in human IMA and RA. Cumulative concentration (−10 ~ −5.5 log M)‐relaxation curves for acetylcholine (ACh) were established in IMA and RA rings (n=6) pretreated with/without inhibitor of SKCa (apamin, 100 nM) or IKCa (charybdotoxin, ChTX, 100 nM). Expression levels of SKCa and IKCa in the whole tissue and smooth muscle cells (SMC) of IMA and RA were quantitated with real‐time PCR. The relaxation curve to ACh was depressed significantly ( p < 0.001) by apamin (29.5 ± 2.9% vs. control 55.5 ± 4.2%) and less by ChTX (44.0 ± 5.2%, p < 0.001) in IMA. In RA, the inhibition of apamin was less significant (57.1 ± 5.4%, p < 0.05) than ChTX (42.5 ± 8.2 % vs control 67.8 ± 8.9 %, p < 0.001). RT‐PCR showed that expression of SKCa was similar to IKCa in integrated IMA tissues (2.32 ± 0.20 vs. 2.24 ± 0.24, p=0.6), but higher than IKCa in IMA SMC (4.06 ± 0.60 vs 1.30 ± 0.26, p < 0.01). For RA, expression of SKCa was higher than IKCa (3.34 ± 0.44 vs 2.49 ± 0.57, p < 0.05) in both integrated tissue and SMC (30.27 ± 7.86 vs. 1.92 ± 0.58, p < 0.001). Thus, both SKCa and IKCa paly a role in IMA and RA. However, the mRNA expression of these ion channels is different in the endothelium and SMC between IMA and RA. Supported by St. Vincent Foundation, Hong Kong RGC (CUHK4383/03M) & CUHK (4450171, 4450231, 2041305).