SECRETORY RESPONSE TO LINGUAL NERVE STIMULATION IN THE SUBMANDIBULAR GLAND OF THE DOG

Abstract

In an attempt to clarify the relationship between the pattern of afferent impulses and efferent effects, the reflex salivary secretion in the submandibular gland of the dog was measured, applying a fixed number (10-90) of square pulses (each pulse of 0.5 msec duration) in the range of repetition rate (r.r.) of 2-200/ sec to the lingual nerve. The quantity of salivary secretion was, within the range of r.r. 2-200/sec, increased with the number of stimulating pulses. A nearly linear relationship between the logarithm of the quantity of saliva secreted (log Q) and that of the number of stimulating pulses (log M) was observed. Regardless of the number of stimulating pulses, the quantity of secretion was greater at the range of r.r. 2-20/ sec than at higher rates. As a comparison, the efferent nerve (the submandibular branch of the chorda tympani nerve) to the submandibular gland was stimulated. Similar results were obtained, however, the r.r. of 2-10/ sec was the optimal frequency only when the number of stimulating pulses was 50 or more. The relationship between r.r. and the number of stimulating pulses necessary to elicit the secretion was investigated. The change caused by the elimination of the other fibres than the taste one in the lingual nerve (by cutting the mandibular nerve of the trigeminal nerve) was studied. Based on these experimental results, the central processing mechanisms of the afferent impulses from the tongue were discussed.