CHANGES IN THE SUBMAXILLARY SECRETORY RESPONSE TO PILOCARPINE AFTER SECTION OF THE CHORDA TYMPANI

Abstract

In 5 dogs with double submaxillary fistulae the salivary response to pilocarpine was investigated before and after section of the chorda tympani. In each animal, only 1 submaxillary gland was deprived of its parasympathetic nerve supply, the other serving as a control. The tests were carried out on the unanesthetized dog. A saline soln. containing 2 mg.% pilocarpine was injected intraven. at a constant rate (30-40 cc. per hr., depending upon body wt.) for exactly 20 min. The rate of secretion was observed for 30-min. In all control expts. the secretion curves from the right and left glands were identical. Within a few days after its chorda tympani had been severed, the submaxillary gland responded more readily to pilocarpine; the secretion not only appeared more promptly but in greater amt. than from the normal control gland. This effect appeared within 6 days, developed fully in 2-3 wks. and was found un-diminished 6 mos. or even 1 yr. after denervation. Evidence is presented that the increased response to pilocarpine of the submax. gland deprived of its parasympathetic nerve supply is not due either to a sudden release of performed salivary substances or to a more abundant blood flow through the gland. Also it does not appear to be the result of sensitization of the parasympathetic nerve endings since the denervated gland responds less well to acetylcholine than does the normal. The essential difference between the response of the denervated and normal submaxillary gland to pilocarpine is not obliterated when the parasympathetic nerve endings have been paralyzed with large intraven. injs. of quinine hydrochloride.