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Distributions of alpha 2 adrenoceptor subtypes in porcine coronary vasculature
Author(s) -
Ho Eva Y.W.,
Leung George P.H.,
Man Ricky Y.K.,
Vanhoutte Paul M.,
Ng K.F.J.
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.914.10
Subject(s) - coronary arteries , adrenergic receptor , immunohistochemistry , medicine , blood vessel , messenger rna , endothelium , alpha (finance) , cardiology , vasodilation , artery , receptor , endocrinology , chemistry , biochemistry , surgery , construct validity , patient satisfaction , gene
Alpha 2‐adrenoreceptor agonists affect vascular tone of coronary vasculature by multiple mechanisms. One of the mechanisms is the direct action on endothelial α2 adrenoreceptors (mainly α2A), which induces an endothelial‐dependent vasorelaxation via release of nitric oxide. We sought to investigate the subtypes of α2 adrenoceptors and their relative abundance in coronary blood vessels of different sizes (arteries vs arterioles). Result of RT‐PCR clearly demonstrated that mRNA of α2A and α2B adrenoceptors was present in coronary arteries but mRNA of α2C‐adrenoceptors was absent. In contrast, mRNA of α2B and α2C adrenoceptors was present in subendocardial myocardium (which contains coronary arterioles) but mRNA of α2A adrenoceptors was not. While mRNA of α2B adrenoceptors were detected in both coronary arteries and subendocardial myocardium, quantitative analysis revealed that its expression was higher in coronary arteries. Immunohistochemical studies showed that α2A and α2B adrenoceptor proteins were located mainly on the endothelial cells of coronary arteries but none was visualized in coronary arterioles. Distributions and cellular localizations of α2C adrenoceptor proteins had not yet been studied since specific antibody was not available. This preliminary data suggests that coronary blood vessels of different sizes may respond differently to pharmacological agents.