Muscarinic acetylcholine receptors (M(1)-M(5)) regulate many key functions of the central and peripheral nervous system. Primarily because of the lack of receptor subtype-selective ligands, the precise physiological roles of the individual muscarinic receptor subtypes remain to be elucidated. Interestingly, the M(4) receptor subtype is expressed abundantly in the striatum and various other fore...

The muscarinic acetylcholine receptor of porcine cerebrum has been purified to apparent homogeneity by affinity chromatography, with conjugated 3-(2'-aminobenzhydryloxy)tropane (ABT) as described previously (Haga, K., and Haga, T. (1983) J. Biol. Chem. 258, 13575-13579). In a single step purification using 900 ml of digitonin/cholate-solubilized preparations and 300 ml of the ABT-agarose gel, w...

Xanomeline is a potent agonist that is functionally selective for muscarinic M(1) receptors. We have shown previously that a significant fraction of xanomeline binding to membranes of Chinese hamster ovary (CHO) cells expressing the M(1) receptors occurs in a wash-resistant manner and speculated that this persistent binding likely does not take place at the primary binding site on the receptor....

Jolkkonen, M., 1996. Muscarinic Toxins from Dendroaspis (Mamba) Venom: Peptides Selective for Subtypes of Muscarinic Acetylcholine Receptors. Acta Univ. Ups., Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 183. 52 pp. Uppsala. ISBN 91-554-3675-7 Snake venoms from various mamba species contain peptides which bind to the muscarinic but not to the nicot...

The present study investigates the interaction of aqueous leaf extract of Psidium guajava with muscarinic, serotonergic and adrenergic receptor system using isolated rat ileum, gastric fundus and trachea, respectively. The concentration-dependent contractile response of aqueous leaf extract of Psidium guajava was parallel and rightward of standard agonists, ACh and 5-HT indicating agonistic act...

Acetylcholine is a neuromodulator that shapes information processing in different cortical and subcortical areas. Cell type and location specific cholinergic receptor distributions suggest that acetylcholine in macaque striate cortex should boost feed-forward driven activity, while also reducing population excitability by increasing inhibitory tone. Studies using cholinergic agonists in anesthe...

The ability of muscarinic cholinergic agonists to interact with muscarinic receptors in nerve ending preparations and elicit an increased labeling of phosphatidate and phosphatidylinositol from 32Pi has been investigated. Two groups of brain muscarinic agonists are distinguished. Addition of acetylcholine, carbamylcholine, methacholine, or muscarine resulted in a 2-fold stimulation of phosphati...

Structure-function relationship studies of the m3 muscarinic acetylcholine receptor have recently identified a series of threonine and tyrosine residues (all located within the hydrophobic receptor core) that are critically involved in acetylcholine binding (Wess, J., Gdula, D., and Brann, M.R. (1991) EMBO J. 10, 3729-3734). To gain further insight into the functional roles of these amino acids...

Fish exposed to hypoxia develop decreased heart rate, or bradycardia, the physiological significance of which remains unknown. The general muscarinic receptor antagonist atropine abolishes the development of this hypoxic bradycardia, suggesting the involvement of muscarinic receptors. In this study, we tested the hypothesis that the hypoxic bradycardia is mediated specifically by stimulation of...

Several motifs found in the third intracellular loop of the M(3) muscarinic receptor are critical for G protein activation and scaffold protein interaction. However, how multiprotein complexes form is not fully understood. A minigene encoding the third intracellular loop of the M(3) muscarinic receptor was constructed to explore whether peptides from this intracellular region could act as inhib...