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Freshly isolated bovine coronary endothelial cells do not express the BK ca channel gene
Author(s) -
Gauthier Kathryn M.,
Liu Caiqiong,
Popovic Aleksandra,
Albarwani Sulayma,
Rusch Nancy J.
Publication year - 2002
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2002.029843
Subject(s) - iberiotoxin , bk channel , microbiology and biotechnology , chemistry , vascular smooth muscle , protein subunit , scn3a , potassium channel , biology , g alpha subunit , biophysics , gene , smooth muscle , endocrinology , biochemistry
Recent reports have suggested that different types of Ca 2+ ‐activated K + channels may be selectively expressed either in the vascular endothelial cells (ECs) or smooth muscle cells (SMCs) of a single artery. In this study, we directly compared mRNA, protein and functional expression of the high‐conductance Ca 2+ ‐activated K + (BK Ca ) channel between freshly isolated ECs and SMCs from bovine coronary arteries. Fresh ECs and SMCs were enzymatically isolated, and their separation verified by immunofluorescent detection of α‐actin and platelet/endothelium cell adhesion molecule (PECAM) proteins, respectively. Subsequently, studies using a sequence‐specific antibody directed against the pore‐forming α‐subunit of the BK Ca channel only detected its expression in the SMCs, whereas PECAM‐positive ECs were devoid of the α‐subunit protein. Additionally, multicell RT‐PCR performed using cDNA derived from either SMCs or ECs only detected mRNA encoding the BK Ca α‐subunit in the SMCs. Finally, whole‐cell recordings of outward K + current detected a prominent iberiotoxin‐sensitive BK Ca current in SMCs that was absent in ECs, and the BK Ca channel opener NS 1619 only enhanced K + current in the SMCs. Thus, bovine coronary SMCs densely express BK Ca channels whereas adjacent ECs in the same artery appear to lack the expression of the BK Ca channel gene. These findings indicate a cell‐specific distribution of Ca 2+ ‐activated K + channels in SMCs and ECs from a single arterial site.