Muscarinic Cholinergic Binding in Rat Brain

AUTOR(ES)

Yamamura, Henry I.

RESUMO

Binding sites with high affinity and specificity for [3H]quinuclidinyl benzilate (QNB) are present in homogenates of rat brain. The characteristics of the binding sites resemble those of muscarinic cholinergic receptors. Specific binding is saturable with respect to [3H]QNB and tissue concentration and is time-, temperature-, and pH-dependent. The bimolecular rate of association (2.0 × 108 M-1 min-1) and dissociation (1.2 × 10-2 min-1) at 35° indicate a dissociation constant of 60 pM and a density of 65 pmol/g of brain. Muscarinic antagonists and agonists displace specific [3H]QNB binding, while nicotinic and non-cholinergic drugs possess little affinity for [3H]QNB-binding sites.

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