Acute amitriptyline effects on parasympathetic-evoked rat saliva.

The present study was undertaken to investigate the acute effects of amitriptyline on salivary secretion evoked by electrical stimulation of the parasympathetic innervations of rat salivary glands. Single intravenous injections of amitriptyline (0.1-1 mg/kg) caused a dose-related decrease in flow and Na concentration of saliva from both parotid and submandibular glands. However, the only effect on K concentration was a slight increase when the salivary flow was almost completely inhibited. Amitriptyline increased the Ca concentration of nerve-evoked submandibular saliva, but had no effect on the Ca concentration of similarly evoked parotid saliva. However, amitriptyline (0.5 and 1 mg/kg) increased the protein concentration of both kinds of saliva. Amylase activity of parotid saliva was also moderately increased by amitriptyline. These effects were similar to those observed with atropine, a known cholinergic receptor antagonist. These results suggest that amitriptyline, like atropine, reduces parasympathetic-evoked salivary secretion by blocking cholinergic receptors.