240 1. lODO ACETATE AND lODOACETAMIDE 



mated to attain a Qco, o^ around 20 by De Eoetth (1954). This is inhibited 

 75% aerobically and 67% anaerobically by 1 mM iodoacetate, so that 

 either the inhibitor does not penetrate well or the glycolytic system is 

 relatively insensitive. Accumulation of iodide by the rabbit ciliary body- 

 iris preparation is strongly inhibited by iodoacetate, 50% reduction of the 

 tissue/medium ratio being produced by 0.2 mM (Becker, 1961). Iodoacetate 

 also causes rather marked hydration of the cornea (Philpot, 1955; Harris, 

 1957). It is thus clear that the retina is not the only sensitive ocular tissue, 

 and in animals treated with the higher dosages of iodoacetate many changes 

 of varying degrees have been noted in lens, cornea, and ciliary body. How- 

 ever, there is no doubt that the retina is the most sensitive to iodoacetate. 



EFFECTS ON MISCELLANEOUS CELL AND 

 TISSUE FUNCTIONS 



A few examples of the actions of iodoacetate on relatively little studied 

 functions, for the most part some form of protoplasmic motility, will be 

 briefly presented, not so much for the information they contain but that 

 they may stimulate more work in some of these fields. 



Salivary Secretion 



Stimulation through the nerve produces a rise in secretion and an output 

 of lactate in the isolated perfused submaxillary gland of the cat (Ferrari 

 and Hober, 1933). It can be calculated that 0.054 mM iodoacetate reduces 

 secretion and lactate formation 81%, and simultaneously the Cl~ concen- 

 tration rises markedly. Acetylcholine similarly stimulates the cat salivary 

 gland (increased secretion, lactate, and respiration) and iodoacetate at low 

 concentrations (0.027 mM) depresses this response to acetylcholine (Druck- 

 rey and Loch, 1943). Somewhat higher concentrations (0.13 mM) depress 

 the acetylcholine response completely, and respiration slowly and partially; 

 the highest concentration used (0.54 mM) reduces the respiration to zero 

 and kills the tissue. Here, in contrast to muscle, the depression of lactate 

 formation (measured as COj produced) runs more or less parallel with the 

 depression of the response to acetylcholine, so that it was concluded that 

 this response depends on lactate production. If secretion is indeed closely 

 related to glycolysis, it would be interesting. 



Phagocytosis 



Leucocytes have a rather high capacity for anearobic glycolysis (^c6, i^ 

 around 20) although respiration and aerobic glycolysis are normal relative 

 to other tissues, so that the absolute Pasteur effect is reasonably high. 



