CHAPTER XI 

 METABOLISM 



The respiration of the salivary glands has been measured both in 

 vivo and in vitro by a number of workers. The resting oxygen con- 

 sumption in dog submaxillary glands is 22-27 / y l-/g- mm (Barcroft, 

 1914; Barcroft and Kato, 1916; Terroux, Sekelj and Burgen, 1959) 

 and in the cat 29 /d./g. mm (Stromblad, 1959). With isolated gland 

 slices or minces somewhat higher values are usually found (Deutsch 

 and Raper, 1936; Brock, Druckrey and Herken, 1938; Stromblad, 

 1957). The respiration rates are quite similar in the various 

 glands from different mammalian species. The R.Q. at rest has 

 been reported between 0-91-1-02 (Barcroft, 1901; Deutsch and 

 Raper, 1938; Stromblad, 1959). With parasympathetic stimulation 

 or injection of acetylcholine or pilocarpine the oxygen consumption 

 rises rapidly to a maximum of 130 to 175 //l./g. min. In both the 

 cat and the dog the increase in respiration is linearly related to 

 the saliva flow rate, but the dog requires only 300 /A. 2 /ml. saliva 

 secreted compared with 630 for the cat. Barcroft and Kato (19 16) 

 found that if the dog submaxillary gland was stimulated over a 

 long period (3 hours) by pilocarpine infusion there was a progres- 

 sive rise in both the blood flow and oxygen consumption required 

 for saliva secretion. After 3 hours 1-3 ml. of oxygen was required 

 for each ml. of saliva produced. Over a shorter period of time the 

 same phenomenon had been encountered. Following a period of 

 stimulation a moderate oxygen debt develops which is mostly 

 dissipated in a few minutes. The R.Q. of the active glands was 

 found to be increased up to 1-8-3-7 by Stromblad (1959), but on 

 the other hand no consistent change was seen by Barcroft (1914). 

 Barcroft and Miiller (19 12) found no correlation between changes 

 in blood flow per se and oxygen consumption in experiments in 

 which yohimbine was injected. This drug produced a striking 

 increase in blood flow through the gland without either salivary 

 secretion or the slightest change in oxygen consumption. Strom- 

 blad (1959), however, suggests that the carbon dioxide output may 

 be dependent on blood flow. 



When adequate doses of atropine are given no saliva secretion 



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