Paroxysmal Secretion 1 1 7 



normal gland there was no flow of saliva. This is the ordinary 

 finding in cats under chloralose anaesthesia. 



During a period of activity the flow is not constant in rate but 

 occurs in bursts, and this type of secretion has therefore been 

 termed "paroxysmal". A drop forming slowly at the tip of the 

 cannula in the parotid duct can be seen to increase suddenly in 

 size and sometimes to fall quickly; after a short time the flow 

 subsides and the drop forms slowly again until another sudden 

 burst occurs. The start of a paroxysm is in most instances readily 

 discernible, and it can then be seen that the bursts appear at 

 remarkably regular intervals, usually of about one minute. 



When the auriculo-temporal nerves are divided at the same time 

 on both sides one to three days in advance it is found that the 

 paroxysmal secretion of one gland occurs independently of that of 

 the other. This suggests that the secretion results from local events 

 rather than from general changes, such as in the composition of 

 the blood. Cocaine injected into the duct towards the gland in a 

 dose which does not affect the secretory response to intravenous 

 acetylcholine abolishes the paroxysmal secretion. It can therefore 

 be concluded that the secretion is of nervous origin. Since it is 

 increased by eserine and abolished by atropine, the nerves con- 

 cerned must be assumed to be cholinergic. It is reasonable to sup- 

 pose that the secretion is caused by some activity in the degenerat- 

 ing postganglionic fibres. It might be supposed that bursts of im- 

 pulses originating from the cut ends of the nerves elicit the paro- 

 xysms of secretion. This is, however, disproved by the findings 

 that the secretion is not abolished when a piece of the degenerating 

 nerve stump is cut off in an acute experiment nor when a local 

 anaesthetic is applied to the stump. A possible explanation may be 

 that a leakage of acetylcholine, normally occurring at a regular 

 rate from the postganglionic parasympathetic terminals, during 

 degeneration of the fibres occurs less regularly, in bursts, so that a 

 concentration of acetylcholine is sometimes reached which is big 

 enough to cause a secretion. 



REFERENCES 



BERNARD, c. (1862). Recherches experimentales sur les ganglions du grand 

 sympathique. C.R. Acad. Sci., 55, 34 J -350- 



