64 II. DIGESTION AND ABSORPTION OF FATS 



and Whatley 372 reported the presence of the acetylcholine-synthesizing en- 

 zyme in spleen, when fiavine adenine dinucleotide was also present. Com- 

 line 373 noted the occurrence of the enzyme in placenta. Holland and 

 Greig 374 found an active choline acetylase in human red blood cells. The 

 presence of this enzyme in red blood cells, as well as the previous demon- 

 stration of its occurrence in placenta, both of which tissues have no in- 

 nervation, proves that the formation of acetylcholine is not necessarily 

 associated with nerve function. Holland and Greig 374 suggest that 'the 

 formation and breakdown of acetylcholine, as reflected by the enzymes 

 present in the particular tissues involved, is related to some general phe- 

 nomenon such as control of permeability changes, which is a property of 

 living cells, whether or not they are innervated. 



(d) Factors Altering the Activity of Choline Acetylase. The activity of 

 choline acetylase is dependent upon the presence of the coenzyme and of 

 other products. The presence of magnesium and manganese were shown 

 by Nachmansohn and Berman 370 to enhance the activity of the enzyme. 

 McLennan and Elliott 375 report that the synthesis of acetylcholine by rat 

 brain slices is augmented by a high potassium ion concentration and in- 

 hibited by lack of calcium ions. These workers also confirm the similar 

 but less marked effect of magnesium ions. The synthesis of acetylcholine 

 by supplemented brain extracts is strongly dependent upon the ATP 

 concentration. 376 Because of the action of apyrase, respiring brain sus- 

 pensions contain virtually no ATP. 376 As early as 1943, Nachmansohn 

 and collaborators 377 reported that L(-f-)-glutamic acid increased the rate of 

 acetylcholine formation four to five times, while D(+)-glutamic acid had 

 practically no effect. It was suggested that l(+) -glutamic acid might be a 

 coenzyme of choline acetylase. 



The extent of acetylcholine synthesis was found to be decreased by 44% 

 in the brains of hypophysectomized rats, as compared with the rate in 

 sham-operated controls. 378 The administration of adrenocorticotropic 

 hormone (ACTH) to such hypophysectomized rats induced an increase in 

 the rate of synthesis of acetylcholine in the brain. In a later study, Torda 

 and Wolff 379 showed that a parallelism exists between acetylcholine syn- 



372 R. S. Comline and F. R. Whatley, Nature, 161, 350-351 (1948). 



373 R. S. Comline, J. Physiol, 105, 6P-7P (1946). 



374 W. C. Holland and M. E. Greig, Arch. Biochem., 39, 77-79 (1952). 



375 H. McLennan and K. A. C. Elliott, Am. J. Physiol., 163, 605-613 (1950). 



376 H. McLennan and K. A. C. Elliott, Arch. Biochem., 36, 89-96 (1952). 



377 D. Nachmansohn, H. M. John, and H. Waelsch, J. Biol. Chem., 150, 485-486 (1943). 



378 C. Torda and H. G. Wolff, Am. J. Physiol, 161, 534-539 (1950). 



379 C. Torda and H. G. Wolff, Am. J. Physiol., 169, 140-149 (1952). 



