Expression of muscarinic receptor genes in the human coronary artery

The authors investigated the role of muscarinic receptors in functional con trol of coronary arteries affected by intimal thickening due to arterioscle rosis. They first examined the genetic subtypes of muscarinic receptors exp ressed in human coronary arteries. Twelve samples of human coronary artery, obtained by autopsy from eight subjects, were examined for the expression of four genetic subtypes of muscarinic receptor, mi to m4, by reverse trans cription and polymerase chain reaction (RT-PCR). Two subtypes, m2 and m3, w ere found to be expressed in the coronary artery. The m2 gene was expressed in seven of the 12 vessels, and m3 in eight of the 12. Expression of both m2 and m3 genes was observed in five of the :12 vessels. Neither the mi nor m4 was expressed in these samples. These results indic;lte that the m2 and m3 genes are mainly expressed in the coronary arteries and suggest that th ese patterns of expression are differentially controlled to induce the dive rsity of contraction/relaxation reactions induced in the coronary arteries by acetylcholine.