Halothane effects on muscarinic acetylcholine receptor complexes in rat brain.
Muscarinic acetylcholine receptors in membranes from rat cerebral cortex or brainstem were equilibrated with halothane (0.5 to 5%). Halothane did not affect the number of [3H]methylscopolamine [( 3H]MS) binding sites. [3H]MS binding affinity, however, was increased in the presence of halothane (KD, air = 0.41 nM; KD, 2% halothane = 0.26 nM). This increase reflected a decrease in the dissociation rate constant (from 13 X 10(-3) min-1 to 6.5 X 10(-3) min-1) rather than a change in the bimolecular rate constant of association (1.8 and 1.9 X 10(7) M-1 min-1 in the absence and presence of 2% halothane respectively). Carbamylcholine affinity for brainstem or cortical muscarinic receptors was not affected by halothane. The ability of a guanine nucleotide to lower carbamylcholine affinity for brainstem receptors, however, was eliminated after equilibration with 2% halothane.
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D001933:Brain Stem / Q000378:metabolism; D002217:Carbachol / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D006221:Halothane / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D019832:N-Methylscopolamine; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects*; D012602:Scopolamine Derivatives / Q000378:metabolism
D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D002217:Carbachol; D006221:Halothane; D019832:N-Methylscopolamine