Secretory responses to autonomic stimulation of rat salivary glands following reserpine treatment.

The response to stimulation of the parasympathetic innervation to parotid or submandibular glands of reserpinized rats was altered from that of untreated rats. Thus, acute reserpinization, like other types of sympathectomy, resulted in increase in volume of parasympathetically-evoked parotid or submandibular saliva when comparison was made with evoked saliva from untreated glands. As norepinephrine is depleted by reserpine, there was no response to stimulation of sympathetic nerves to these reserpinized glands. Adrenergic receptors were normally activated by administration of autonomic agonists. Thus a single high dose of reserpine can cause the same effects as those induced by chronic administration of low doses of reserpine, i.e. a 3-fold increase in calcium (Ca) concentration of submandibular gland but no change in Ca concentration of parotid gland. Although sympathetic stimulation caused no change in Ca concentration of submandibular or parotid glands of reserpine (acute)-treated rats, stimulation with isoproterenol (25 mg/kg, i.p., 60 min) produced a 32-35 per cent decrease in glandular Ca concentration from that of unstimulated reserpinized glands. Glands of untreated rats showed a 52 per cent depletion after 60 min of isoproterenol stimulation; however, Ca output in parotid saliva from reserpinized rat for 60 min of stimulation was not changed from that of untreated rats, but that of submandibular saliva was two times greater. Ca concentration of submandibular saliva was unchanged during 60 min-stimulation of reserpine-treated rats, but that of untreated rats decreased.