Effects of Chinese herbs on salivary fluid secretion by isolated and perfused rat submandibular glands

Abstract

To determine whether Chinese herbs (CHs) relieve xerostomia (dry mouth) by increasing salivary secretion. The submandibular glands of Wistar rats were surgically isolated and perfused arterially with buffered salt solution. After control perfusion, recording started 5 min prior to the start of stimulation. After fluid secretion was induced by 0.2 mumol/L carbamylcholine (CCh) in the perfusate for 10 min, Chinese herb (CH) was added in the perfusion for 5 min. CCh was then overloaded at 0.2 mumol/L in the perfusion for 20 min. The volume of salivary fluid secretion was recorded by a computer-controlled balance system. Saliva secretion formed an initial ephemeral peak at 30 s followed by a gradual increase to a sustained level. CH alone induced no or little saliva in all types of CH selected. During perfusion with CH, overloading of CCh promoted fluid secretion in 15 of 20 CHs. This promotion was classified into four patterns, which were eventually related to the categories of CH: Overall sustained phase was continuously raised (Yin-nourishing, fluid production-promoting and heat-clearing agents); The sustained secretion rose to reach a maximum then decreased (Qi-enhancing agent); Sustained secretion rose to reach the highest maximum and was then sustained with a slight decline (swelling-reducing, phlegm-resolving and pus-expelling agents); Stimulation of salivary secretion without any added stimulants. Addition of CCh raised the fluid secretion to reach the highest maximum then sharply decreased to a lower sustained level (blood activating agent). The present findings lead to the conclusion that various CHs have different promotional effects directly on the salivary gland.