3ubtypes of muscarmic receptors, first hypothesized by Birdsall et al. ~ to explain the anomalous binding of cholinergic agonists to brain receptors~ were later demonstrated with the seEective muscarinic antagonist, pirenzepine 2. Interestingly, the search for selective antagonists, which usually follows the acceptance of a concept, antedated by many years the notion of heterogeneity of rmecari...
