Aceclidine and pilocarpine interact differently with muscarinic receptor in isolated rabbit iris muscle.
The relationship between muscarinic receptor affinity states and the contractile response to the muscarinic agonists carbachol, aceclidine, and pilocarpine, has been examined in the isolated rabbit iris muscle. Contraction of the iris muscle by carbachol and aceclidine was more potent and/or more efficacious than the response to pilocarpine. Analysis of [3H]-Quinuclidinyl benzilate (QNB) binding showed that while both carbachol and aceclidine bound to high- and low-affinity forms of the muscarinic receptor, pilocarpine bound to one affinity state. The efficacy of carbachol and aceclidine to stimulate contraction of the iris muscle was consistent with receptor occupancy theory only when considering the low-affinity state of the muscarinic receptor, and activation of the low-affinity rather than high-affinity binding state of the receptor is likely to mediate the contraction of iris muscle. Therefore, the typical anti-glaucoma muscarinic agonists aceclidine and pilocarpine may interact differently with their target receptors in isolated rabbit iris muscle.
Zhu
Liang
L
Institute of Drug Research, Shanghai Second Medical University, 280 South Chongqing Road, Shanghai 200025, China.
Cui
Yong-Yao
YY
Feng
Ju-Mei
JM
Wu
Xing-Jun
XJ
Chen
Hong-Zhuan
HZ
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D007498:Iris / Q000502:physiology*; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D010862:Pilocarpine / Q000494:pharmacology*; D011812:Quinuclidines / Q000494:pharmacology*; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects*
D018721:Muscarinic Agonists; D011812:Quinuclidines; D011976:Receptors, Muscarinic; D010862:Pilocarpine; C084650:aceclidine; D002217:Carbachol