Effects of saliva from chronically reserpinized rat on Na and K transport in perfused main excretory duct of submandibular gland of normal rat.

Reserpine (RES) (0.5 mg/kg body wt, ip) was administered to rats for 7 days. On Day 8 saliva was evoked from these animals by intraperitoneal injection of pilocarpine nitrate (10 mg/kg body wt) and saliva from submandibular and parotid glands was collected separately. These collected salivas were used to perfuse through the main ducts of the submandibular glands of normal rats. After a control period of perfusion of the main duct with bicarbonate saline solution, parotid saliva from RES rats was perfused through the duct followed by regular perfusion. There was inhibition of Na absorption (22%) and K secretion (23%). Moreover, when submandibular saliva from treated rat was perfused through the main duct prior to regular perfusion, there was a decrease in Na absorption (31%) and K secretion (28%). In contrast, perfusion of the main duct with either parotid or submandibular saliva from normal rats caused no significant changes in Na and K transport. The present experiments confirm previous studies that there is some Na-inhibitory factor(s) present in saliva of the chronically RES-treated rat.