232 Metabolism 



is maintained for many hours. The acetylcholine effect, however, 

 is readily attenuated when there is no added substrate and is con- 

 siderably augmented by the addition of large amounts (100-200 

 mg/100 ml.) of lactate. This effect of lactate is prevented by the 

 simultaneous addition of small amounts of glucose. The Qo 2 in 

 the presence of iodacetate is also increased by lactate. Anaerobic 

 glycolysis is not very active except in the presence of glucose and 

 is not satisfactorily maintained by fructose (Deutsch and Raper, 

 1938; Brock, Druckrey and Loch, 1942). Dinitrophenol increases 

 the Qo 2 of the resting gland to the maximum found after addition 

 of acetylcholine (Stromblad, 1957). 



When gland atrophy was produced in the rat by a duct ligation, 

 the Qo 2 was reduced to 40 per cent of normal and similar reduc- 

 tions occurred in pyruvate oxidation, succinic dehydrogenase and 

 the content of high energy phosphates. No change was found in 

 glycolysis (Junqueira, 1955; Junqueira and Hirsch, 1956). It has 

 been pointed out elsewhere (page 225) that a high concentration 

 of mitochondria, succinic dehydrogenase, and the rich vasculari- 

 zation of the salivary ducts suggests that a considerable fraction 

 of the total gland respiration is due to these elements. 



PHOSPHORUS TURNOVER 



Extensive studies on phospholipid turnover in the salivary 

 glands, pancreas, brain and other tissues have been carried out by 

 the Hokins (Hokin and Hokin, 1953, 1954, 1958, 1959^2 and b). 

 They found that P 32 incorporation into the phospholipids of rab- 

 bit parotid and submaxillary and guinea pig parotid slices was 

 increased several fold by the addition of acetylcholine and adrena- 

 line. These effects could be prevented by atropine and ergotamine, 

 dibenamine or chlorpromazine, respectively. Noradrenaline was 

 less effective than adrenaline. Submaximal doses of adrenaline and 

 acetylcholine were additive, but maximal effects were not additive. 

 In the rabbit but not in the guinea pig parotid, increased incor- 

 poration of P 32 into the acid-soluble phosphate esters also occurred. 



Under anaerobic conditions the stimulating effect of carbamyl- 

 choline on phospholipide synthesis in the pancreas is no longer 

 present (Hokin and Hokin, 1953). Further analyses of these effects 

 have been carried out in the pancreas and the brain and since it 

 seems likely that these do not differ in any important degree from 

 the effect in the salivary glands they are relevant to our account. 



