[Muscarinic acetylcholine receptors in peripheral human lung tissue: binding characteristics of 3H-quinuclidinyl-benzilate in malignancies].

Binding of muscarinic receptors antagonist 3H-quinuclidinyl benzylate (3H-QNB) was studied in human peripheral lung tissue, obtained after resection of pulmonary carcinoma and partial resection of tuberculoma from surrounding normal tissues (control group). Radioligand binding assays showed that binding of 3H-QNB in lung parenchyma membranes of both normal, healthy persons and patients with cancer was saturable with high rate of affinity. Saturation occurred at 1 nm concentration of the ligand. The Scatchard plot analysis indicated that the high affinity binding site exhibited the following parameters: Kd = 0.33 nm, Bmax = 164.8 fmol/mg in the group of controls: and Kd = 0.63 nm, Bmax = 401.5 fmol/mg in the group of patients with cancer. Maximal amount of 3H-QNB binding sites was distinctly increased in malignization of peripheral lung tissue. The results obtained suggest that increase in concentration of 3H-QNB binding sites may be among the specific patterns of malignant growth in lung peripheral tissue.