Cholinergic Responses of Ophthalmic Arteries in M3and M5Muscarinic Acetylcholine Receptor Knockout Mice

PURPOSE. To determine the functional role of M 3 and M 5 muscarinic acetylcholine receptor subtypes in ophthalmic arteries using gene-targeted mice. METHODS. Muscarinic receptor gene expression was quantified in murine ophthalmic arteries using real-time PCR. To test the functional relevance of M 3 and M 5 receptors, ophthalmic arteries from mice deficient in either subtype (M3R -/- , M5R -/- , respectively) and wild-type controls were isolated, cannulated with micropipettes, and pressurized. Changes in luminal vessel diameter in response to muscarinic and nonmuscarinic receptor agonists were measured by video microscopy. RESULTS. With the use of real-time PCR, all five muscarinic receptor …