Miscellaneous Agents 85 



on one hand from secretion and dilatation on the other (Emmelin, 

 1955). A suitable dose of chlorpromazine may preferentially abolish 

 the secretion and dilatation, one of priscol, the constriction. 

 Bretylium abolishes the secretory and constrictor effects of sym- 

 pathetic stimulation (Emmelin and Engstrom, i960). 



MISCELLANEOUS AGENTS 



Potassium. A few mg of potassium chloride injected close arteri- 

 ally into the submaxillary gland of a cat may have a slight secretory 

 effect. The response is considerably increased by eserine and is due 

 to local liberation of acetylcholine in the gland by the potassium 

 (Feldberg and Guimarais, 1936). 



Barium. When studying the contractile mechanism of the sali- 

 vary glands which can be activated by sympathetic stimulation, 

 adrenaline or histamine, Stavraky (1932) examined the action on 

 the glands of barium. Contrary to what was expected, the action 

 of barium was secretory in effect. This was increased by eserine 

 and abolished by atropine. In some cases the response was not 

 completely annulled by atropine. This might perhaps indicate that 

 the secretory effect was partly due to adrenaline released from the 

 suprarenals, for the doses causing secretion were apparently not 

 far below a lethal level. 



Mercury. Mercurial ptyalism is well known and many attempts 

 have been made to reveal its mechanism. Several possibilities have 

 to be taken into account. The hypersalivation may be secondary to 

 the stomatitis and elicited reflexly from the mouth. Mering (1881) 

 found, however, in animal experiments that mercury can cause a 

 flow of saliva even if no stomatitis is present and suggested an 

 action either centrally or on the secretory nerves. As to the first 

 possibility, it has been shown (Morgan and Johnson, 1930) that 

 injection of mercury chloride into the tuber cinereum-region in 

 dogs causes excessive salivation. The peripheral actions of mercury 

 on the submaxillary gland of dogs have been studied by Melville 

 (1930). He found mercury chloride to increase the effect of chorda 

 stimulation but not of injected pilocarpine and assumed an action 

 on the chorda endings. In this connection it is interesting to ob- 

 serve that mercury compounds have been found to increase the 

 action of vagus stimulation on the heart and the intestinal motility 

 (Salant and Brodman, 1929a and b). A reasonable hypothesis might 

 be that mercury acts by inhibiting cholinesterase. This would be 



