CHAPTER IV 

 PHARMACOLOGY OF SALIVARY SECRETION 



It would seem that the only way of activating the secretory mech- 

 anism of the salivary gland cell is to apply an agent which imitates 

 the action of parasympathetic or sympathetic nerve fibres. As early 

 as 1859, Claude Bernard had shown that the salivary gland cells 

 cannot be excited electrically. It is true that various agents, ordin- 

 arily not classified as autonomic drugs, such as potassium, barium 

 and mercury ions, histamine and some other imidazole derivatives, 

 tetramethylammonium, and an unidentified compound present in 

 saliva, may excite secretion. Common to these substances, how- 

 ever, is that their secretory actions, like that of parasympathetic 

 stimulation, can be abolished by atropine. The only doubtful case 

 may be the secretion caused by some nitrogen mustards, which 

 cannot be interrupted by the administration of atropine ; and it has, 

 in fact, been assumed by some investigators that such agents have 

 a ' 'direct" effect on the secretory mechanism. Nevertheless, if 

 atropine has been given prior to the injection of the nitrogen mus- 

 tard no secretion is evoked. The general statement that no agents 

 can cause a secretion of saliva after the administration of a sym- 

 patholytic or parasympatholytic drug therefore seems to hold 

 good. 



Apart from the various agents, acting within the salivary glands, 

 numerous drugs may of course provoke a flow of saliva by causing 

 a discharge of impulses in the secretory nerves. Such agents may 

 act on receptors from which a salivary reflex can be elicited or on 

 central or ganglionic structures. Correspondingly, salivary secre- 

 tion can, under such circumstances, be abolished not only by sym- 

 patholytic or parasympatholytic agents but by drugs with gan- 

 glionic blocking or central depressant action as well. Generally, it 

 seems to be true that salivary secretion is very susceptible to a 

 blocking action, exerted peripherally, ganglionically or centrally. 

 It is a common experience that dryness of the mouth is one of the 

 more frequent side effects of therapeutic agents. Henderson (1923) 

 studied the sensitivity to atropine of various structures supplied 

 with nerves from the bulbosacral outflow and found the following 



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