Failure to Confirm Muscarinic Receptors on Skin Fibroblasts

To the Editor: In the July 26 issue, Nadi et al.¹ reported that primary cultures of human skin fibroblasts “possess muscarinic receptors with the properties of specific binding, saturability, pharmacologic specificity, inhibition of norepinephrine-stimulated adenylate cyclase, and increased binding after incubation with an antagonist.” The authors also indicated that the fibroblasts of patients with a major affective disorder (or a relative with a history of a major or minor depressive disorder) had a significantly higher density of muscarinic binding sites as determined by the binding of the radioactive antagonist ligand [³H]quinuclidinyl benzilate ([³H]QNB) than did control subjects. They.