Accession Number : ADA259296


Title :   Prejunctional Muscarinic Receptors in the Deep Muscular Plexus of Canine Ileum: Comparison with Smooth Muscle Receptors


Corporate Author : WALTER REED ARMY INST OF RESEARCH WASHINGTON DC DIV OF BIOCHEMISTRY


Personal Author(s) : Kostka, Peter ; Ahmad, Sultan ; Kwan, Chiu-Yin ; Daniel, Edwin E ; Gordon, Richard K


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a259296.pdf


Report Date : Jan 1992


Pagination or Media Count : 7


Abstract : Prejunctional muscarinic receptors from the deep muscular plexus of canine ileum were studied, and their properties were compared with those of the postjunctional receptors of the circular smooth muscle. In the purified synaptosomal fraction (a fraction containing primarily the axonal varicosities of deep muscular plexus), the muscarinic ligand N-(3H)methylscopolamine labeled an apparently homogenous population of receptors (nH = 1) with a Kd of 2.7 nM and a Bmax of 195 +/- 44 fmol/mg protein (mean +/- S. D., n = 4). These receptors showed a high affinity for the M3/Mi-selective antagonist 4- diphenylacetoxy-N-methylpiperidine methiodide (pKi = 7.41); in contrast, the pKi values of pirenzepine (5.60), methoctramine (5.65) and AF-DX 116 (5.21) implied little selectivity for these subtypes. The binding properties of muscarinic receptors in the synaptosomal fraction were different from the binding properties of muscarinic receptors in the purified circular smooth muscle plasma membranes. Most notably, the circular smooth muscle receptors had significantly lower affinity for N-(3H)methylscopolamine (Kd = 16 nM) with a Bmax value of 2088 +/- 276 fmol/mg. The affinities of the M2 subtype-selective muscarinic antagonists methoctramine and AF-DX 116 were similar in both membrane preparations. The receptor population associated with the deep muscular plexus synaptosomal fraction was linked to the inhibition of adenylate cyclase activity, as demonstrated by a concentration-dependent, atropine-sensitive inhibition of the forskolin-stimulated enzyme in the presence of muscarinic agonists carbachol and oxotremorine.


Descriptors :   *RECEPTOR SITES(PHYSIOLOGY) , *MUSCARINE , *ILEUM , REPRINTS , CONTRAST , MEMBRANES(BIOLOGY) , ENZYMES , PROTEINS , COMPARISON , OBSERVATION , POPULATION , MUSCLE RELAXANTS , CHOROID PLEXUS , CARBACHOL , LABORATORY ANIMALS , ATROPINE , PHARMACOLOGY , AVAILABILITY , LIGANDS , GENES , MEAN , MUSCLES , INHIBITION , CENTRAL NERVOUS SYSTEM


Subject Categories : Biology
      Anatomy and Physiology


Distribution Statement : APPROVED FOR PUBLIC RELEASE