Cholinesterase and transport of sodium chloride through gills c/Eriocheir sinensis (M.Edw.) 



43 mg. of acetylcholine per hour. This figure compares favourably with the figure of 

 5 to 50 mg. given by Nachmansohn (1952) for nerve fibres. 



Eriocheir gill cholinesterase is inhibited by means of basic dyes. Acidic dyes have 

 comparatively speaking little effect, as is apparent from Figure 5. 



O MINUTES 



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30 



40 



Figure 5. Evolution of C0 2 as a consequence of the 



splitting of acetylcholine under the influence of a fine 



suspension of gill tissue in the presence of basic and 



acidic dyes. {Koch, Evans and Schicks, 19546.) 



ACH: control with acetylcholine alone, 



G: in the presence of gallocyanine [acidic dye), 



M: „ „ „ „ methyl blue (acidic dye), 



A: ,, ,, ,, ,, alizarine blue (acidic dye), 

 C: ,, „ ,, ,, crystal violet (basic dye), 

 S: „ „ „ „ safranine T (basic due) , 

 B: „ „ „ „ basic fuchsin (basic dye). 



The blood of the crab itself contains a cholinesterase which is inhibited by means 

 of the same basic dyes as well as other cholinesterase inhibitors. When the blood is 

 expressed as far as possible from the gills before the mixing process a considerable 

 cholinesterase activity remains. It thus seemed highly probable — but not certain — 

 that cholinesterase is present in the gill epithelium itself. 



Basic dyes were then injected into the crab in such concentration as to reach 

 approximately io -3 in the blood; and the gills, deeply stained from the inside, were 

 afterwards tested for active transport. The gills so treated proved to be as active 

 absorbers as normal gills. In this way it became evident that the cholinesterase of 

 the blood, completely inhibited by the presence of the dye, was of no importance for 

 the active absorption process. It also seems hard to escape the conclusion that cholin- 

 -esterase is present along the exterior surface of the gill epithelium and that it is this 



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