[3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart

J. X. Wang, W. R. Roeske, K. Gulya, W. Wang, H. I. Yamamura

Research output: Research - peer-reviewArticle

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Abstract

The in vitro binding properties of the novel muscarinic antagonist [3H]AF-DX 116 were studied using a rapid filtration technique. Association and dissociation rates of [3H]AF-DX 116 binding were rapid at 25°C (2.74 and 2.70 × 107 min-1 M-1 for k+1; 0.87 and 0.93 min-1 for k-1) but 20-40 times slower at 0-4°C (0.13 and 0.096 × 107 min-1 M-1 for k+1; 0.031 and 0.022 min-1 for k-1 in cerebral cortical and cardiac membranes, respectively). Kinetic dissociation constants (Kds) were estimated to be 31.8 nM and 30.9 nM at 25°C ; 23.1 nM and 22.9 nM at 0-4°C for the cerebral cortex and heart, respectively. In saturation studies, [3H]AF-DX 116 labeled 29 percent of the total [3H](-)QNB binding sites in the cerebral cortical membranes and 87 percent in the cardiac membranes, with Kd values of 28.9 nM and 17.9 nM, respectively. Muscarinic antagonists inhibited [3H]AF-DX 116 binding in a rank order of potency of atropine > dexetimide > AF-DX 116 > PZ > levetimide in both tissues. Except for PZ/[3H]AF-DX 116 and AF-DX 116/[3H]AF-DX 116 in the cerebral cortex, all the antagonist competition curves had Hill coefficients close to one. Carbachol and oxotremorine produced shallow inhibition curves against [3H]AF-DX 116 binding in both tissues. Regional distribution studies with [3H](-)QNB, [3H]PZ and [3H]AF-DX 116 showed that most of the muscarinic receptors in the cerebral cortex, hippocampus, nucleus accumbens and corpus striattum are of the M1 subtype while those in the brainstem, cerebellum and other lower brain regions are of the M2 subtype. These results indicate that [3H]AF-DX 116 is a useful probe for the study of heterogeneity of muscarinic cholinergic receptors.

LanguageEnglish (US)
Pages1751-1760
Number of pages10
JournalLife Sciences
Volume41
Issue number14
DOIs
StatePublished - Oct 5 1987

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Cholinergic Receptors
Cholinergic Agents
Rats
Labels
Brain
otenzepad
Muscarinic Receptors
Membranes
Cerebral Cortex
Muscarinic Antagonists
Tissue
Dexetimide
Oxotremorine
Carbachol
Binding Sites
Kinetics
levetimide
Nucleus Accumbens
Atropine
Cerebellum

ASJC Scopus subject areas

  • Pharmacology

Cite this

[3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart. / Wang, J. X.; Roeske, W. R.; Gulya, K.; Wang, W.; Yamamura, H. I.

In: Life Sciences, Vol. 41, No. 14, 05.10.1987, p. 1751-1760.

Research output: Research - peer-reviewArticle

Wang JX, Roeske WR, Gulya K, Wang W, Yamamura HI. [3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart. Life Sciences. 1987 Oct 5;41(14):1751-1760. Available from, DOI: 10.1016/0024-3205(87)90604-7
Wang, J. X. ; Roeske, W. R. ; Gulya, K. ; Wang, W. ; Yamamura, H. I./ [3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart. In: Life Sciences. 1987 ; Vol. 41, No. 14. pp. 1751-1760
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abstract = "The in vitro binding properties of the novel muscarinic antagonist [3H]AF-DX 116 were studied using a rapid filtration technique. Association and dissociation rates of [3H]AF-DX 116 binding were rapid at 25°C (2.74 and 2.70 × 107 min-1 M-1 for k+1; 0.87 and 0.93 min-1 for k-1) but 20-40 times slower at 0-4°C (0.13 and 0.096 × 107 min-1 M-1 for k+1; 0.031 and 0.022 min-1 for k-1 in cerebral cortical and cardiac membranes, respectively). Kinetic dissociation constants (Kds) were estimated to be 31.8 nM and 30.9 nM at 25°C ; 23.1 nM and 22.9 nM at 0-4°C for the cerebral cortex and heart, respectively. In saturation studies, [3H]AF-DX 116 labeled 29 percent of the total [3H](-)QNB binding sites in the cerebral cortical membranes and 87 percent in the cardiac membranes, with Kd values of 28.9 nM and 17.9 nM, respectively. Muscarinic antagonists inhibited [3H]AF-DX 116 binding in a rank order of potency of atropine > dexetimide > AF-DX 116 > PZ > levetimide in both tissues. Except for PZ/[3H]AF-DX 116 and AF-DX 116/[3H]AF-DX 116 in the cerebral cortex, all the antagonist competition curves had Hill coefficients close to one. Carbachol and oxotremorine produced shallow inhibition curves against [3H]AF-DX 116 binding in both tissues. Regional distribution studies with [3H](-)QNB, [3H]PZ and [3H]AF-DX 116 showed that most of the muscarinic receptors in the cerebral cortex, hippocampus, nucleus accumbens and corpus striattum are of the M1 subtype while those in the brainstem, cerebellum and other lower brain regions are of the M2 subtype. These results indicate that [3H]AF-DX 116 is a useful probe for the study of heterogeneity of muscarinic cholinergic receptors.",
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N2 - The in vitro binding properties of the novel muscarinic antagonist [3H]AF-DX 116 were studied using a rapid filtration technique. Association and dissociation rates of [3H]AF-DX 116 binding were rapid at 25°C (2.74 and 2.70 × 107 min-1 M-1 for k+1; 0.87 and 0.93 min-1 for k-1) but 20-40 times slower at 0-4°C (0.13 and 0.096 × 107 min-1 M-1 for k+1; 0.031 and 0.022 min-1 for k-1 in cerebral cortical and cardiac membranes, respectively). Kinetic dissociation constants (Kds) were estimated to be 31.8 nM and 30.9 nM at 25°C ; 23.1 nM and 22.9 nM at 0-4°C for the cerebral cortex and heart, respectively. In saturation studies, [3H]AF-DX 116 labeled 29 percent of the total [3H](-)QNB binding sites in the cerebral cortical membranes and 87 percent in the cardiac membranes, with Kd values of 28.9 nM and 17.9 nM, respectively. Muscarinic antagonists inhibited [3H]AF-DX 116 binding in a rank order of potency of atropine > dexetimide > AF-DX 116 > PZ > levetimide in both tissues. Except for PZ/[3H]AF-DX 116 and AF-DX 116/[3H]AF-DX 116 in the cerebral cortex, all the antagonist competition curves had Hill coefficients close to one. Carbachol and oxotremorine produced shallow inhibition curves against [3H]AF-DX 116 binding in both tissues. Regional distribution studies with [3H](-)QNB, [3H]PZ and [3H]AF-DX 116 showed that most of the muscarinic receptors in the cerebral cortex, hippocampus, nucleus accumbens and corpus striattum are of the M1 subtype while those in the brainstem, cerebellum and other lower brain regions are of the M2 subtype. These results indicate that [3H]AF-DX 116 is a useful probe for the study of heterogeneity of muscarinic cholinergic receptors.

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