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



the frog's skin. Besides all this the acetylcholinesterase has long been known to play 

 a part in the transmission of nerve impulses at the motor end plates of muscles and 

 in synaptic transmission, and it probably also takes part in conduction along the 

 nerves of many species of animals (Fessard and Posternak, 1950; Nachmansohn, 

 1950). We thus find this same enzyme associated with phenomena which in certain 

 of their aspects are intimately associated with active transport of the ions of alkali 

 metals (Hodgkin, 1951; Rothenberg, 1950). 



The action of acetylcholine and cholinesterases on the heart muscles of vertebrates 

 and invertebrates is well known (Krijgsman, 1952), and quite recently Biilbring, 



- Nicotine HCI 



/ 



20 MINUTES. 60 



IOO 120 



Figure 10. Nicotine hydrochloride first accelerates 



but soon depresses the absorption of NaCl by the 



gill of Eriocheir. Removal of the inhibitor does 



not restore the active uptake. 



Burn and Shelley (1953) have shown that cholinesterase and acetylcholine are also 

 essential for the ciliary movements of Mytilus. 



All this seems to suggest that these widely different mechanisms are dependent on 

 some common basic cell activity which may turn out to be an active transport 

 phenomenon, applied in hypertrophic condition, if one may so describe it, for certain 

 functions. 



We do not intend to dwell on further details or to collect a multiplicity of data 

 which do not lead to any further elucidation. Nevertheless I think it is worth while 

 to mention the effect of nicotine (Figure 10) on ion transport in the gills of the crab. 

 It is an inhibitor, but before it inhibits it clearly accelerates the rate of absorption of 

 NaCl. Is this not what from another point of view vertebrate pharmacologists would 

 call a nicotinic effect? Undoubtedly there are big differences as far as effective 



25 



