i5o 



The Inorganic Components of Saliva 



is largely eliminated as the size of the sample is increased (Fig. 8.7). 

 The initial difference in potassium concentration depends on the 

 duration of the rest period since the previous stimulation; and 

 previous authors had missed this inequality of concentrations 

 either because of the large size of the saliva samples that they 

 collected or because of dealing with a continuously secreting gland 

 and discarding earlier "aberrant" samples or because they used 

 very short intervals between collections of samples which did not 



1000 2000 3000 



Size of salivary sample collected (mg/g) 



Fig. 8.7. Dependence of the concentration of potassium in submaxillary 



saliva of the dog on the size of the saliva sample collected. 



(Burgen, 19560.) 



allow the early phase of secretion to appear. In the early phase, 

 potassium concentrations up to 20 times the plasma level may be 

 found. The rest period necessary for the return of the full initial 

 transient concentration of potassium after a period of stimulation 

 was investigated by Seeman (1956). He found that in the dog 

 parotid gland, the transient was half restored by a rest of 2-5 

 minutes whereas in the dog submaxillary gland this required 15-30 

 minutes. Lundberg (1958) has found a similar potassium transient 

 in the cat sublingual secretion. Brusilow and Cooke (1959) found 

 virtually no potassium transient when the rest period was a minute 

 or less. A fuller discussion of the potassium transient, its relation- 

 ship to changes in gland electrolytes and implications for the secre- 



