Muscarinic Receptor Subtypes of Bovine Intraocular Muscles

To ascertain the predominance of muscarinic receptor subtypes in bovine intraocular muscles (ciliary muscle, iris sphincter muscle and iris dilator muscle), each muscle was pharmacologically studied on contraction or relaxation with the following selective muscarinic antagonists: pirenzepine(M1), AF-DX 116(M2), methoctramine(M2) and 4-DAMP (M3). The order of inhibitory effects on carbachol-induced contraction was M3> M1 >M2 in all the muscles. Nerve-mediated responses of these three muscles were most strongly inhibited by the application of 4-DAMP. Moreover, 4-DAMP was much more effective on ciliary muscle than the others in both carbachol- and nerve-mediated contraction. These results indicate that M3 receptor subtype functionally predominates in the bovine intraocular muscles, particularly in the ciliary muscle.

ムスカリン受容体サブタイプ

毛様体筋

瞳孔括約筋

瞳孔散大筋

内眼筋肉