الفهرس 
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Abstract
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SUMMARY AND CONCLUSION
This study illustrates the lack of intrinsic activity of SR
95639A in activating muscarinic receptor-mediated second messenger
signals. This was demonsterated in muscarinic receptor-coupled
responses in cell lines transfected with the genes of MI and M,
receptors, in addition to responses induced by neuronal MI, M2, M,
or ~ muscarinic receptors. Thus, our results do not confirm any
apparent muscarinic agonistic activity for this compound.
Furthermore, they do not show marked selectivity of the compound
among muscarinic receptor subtypes at the level of ligand
reeognition site. Also, activation of striatal muscarinic receptors
linked to neurotransmitters release with muscarinic agonists
depends on the intrinsic activity and affinity state of such
agonists. This was demonsterated in rat striatal muscarinic
receptors coupled to either inhibition of choline release or
potentiation of dopamine release. The results demonstrate that ,
oxotremorine differentiates .between striatal muscarinic receptors
linked to both systems as it was a partial agonl’st at M, receptor
subtype having low affinity for this receptor subtype and a full
agonist with high affinity for M2• The full agonists methacholine
and carbamylcholine had high affinities for both sUbtypes. Also,
pilocarpine and McN-A-343 bind to both subtypes wl’th only low’
affinities.