Characterization of muscarinic cholinergic receptors on rat pancreatic acini by N-[3H]methylscopolamine binding. Their relationship with calcium 45 efflux and amylase secretion.

摘要: N-[3H]Methylscopolamine (NMS) binding, amylase secretion, and 45Ca efflux from dispersed rat pancreatic acini were investigated in parallel, the presence or absence of 4 muscarinic agonists 3 antagonists. Scatchard analysis [3H]NMS saturation isotherms gave a KD 0.9 nM an average binding capacity 24,000 sites per cell. Binding competition curves with antagonists atropine, dexetimide, NMS values 3.5, 0.5 nM, respectively. With full oxotremorine, muscarine, carbamylcholine, receptor population could be divided into two classes sites: minor one (15%) high affinity (KD = 20-35 nM) major (85%) low 3-65 microM). There was reserve about 50% respect to carbamylcholine-stimulated secretion. Further dose-effect suggests that involved secretory response stimulation. Pilocarpine, like antagonists, recognized all same but acted as partial agonist on secretion efflux.