Total Protein Secretion 



183 



quency up to 50 c/s increases the concentration and output of 

 protein without further increase in the flow of saliva (Burgen, 

 Weiss and Seeman, 1959). In human parotid secretion protein 

 concentration seems less closely affected by rate of secretion (Fer- 

 guson, Krahn and Hildes, 1958). More detailed analysis of the 

 output of protein from the dog parotid gland shows at the begin- 

 ning of stimulation a short transient of high protein concentration 



200 300 



Saliva flow rate ml/g min 



Fig. 9.5. Dog parotid secretion. Auriculo-temporal stimulation. 



concentration of protein in saliva when saliva flow rate was altered by changing 



rate of nerve stimulation. — minute output of protein in the saliva. 



followed by a minimum and the rather slow subsequent develop- 

 ment of a steady protein concentration over the following 30 to 100 

 seconds (Fig. 9.6). The earlier protein peak (P x ) is relatively inde- 

 pendent of stimulation conditions and cannot be exhausted by 

 repeated periods of stimulation, but on the other hand is highly 

 dependent on the rest period following the previous period of 

 stimulation. From its time of appearance and these characteristics 

 it appears to result from a continuous secretion of protein from 

 duct cells. In contrast the late phase of protein secretion can readily 

 be exhausted by repeated stimulation and is dependent on stimu- 

 lation frequency; it appears to be the result of acinar secretion 

 of protein. The relatively long latency during which it develops 



