EFFECTS ON PERMEABILITY AND ACTIVE TRANSPORT 



191 



ited by 2,4-dinitrophenol. Antagonistic actions on ATPase were considered, 

 but it is difficult to understand how iodoacetate can inhibit ATPase suffi- 

 ciently at this concentration to conserve ATP, especially in light of its 

 ability to inhibit ATP formation. Furthermore, azide and ffiioride also coun- 

 teract the 2,4-dinitrophenol effect. Phlorizin readily inhibits glucose trans- 

 port in the recirculated rat intestine, but stimulates in the presence of iodo- 

 acetate (Manome and Kuriaki, 1961). Iodoacetate was injected intrave- 

 nously at a dose of 0.5 mg/g, a very high dosage. Furthermore, iodoacetate 

 alone increases 40% the absorption of glucose, which is contrary to all 

 previous reports. An additional aspect not well understood is the transin,- 

 testinal electrical potential which is increased by glucose and is in some 

 manner related to the active transport. Iodoacetate at 0.1 mM depresses 

 the potential progressively and irreversibly (Sawada and Asano, 1963; 

 Barry et al., 1964), which may be the result of reduction in glucose transport. 

 One can only conclude that more work needs to be done before we can 

 understand the actions of iodoacetate on the intestinal transport systems. 



Renal Transport 



The perfused frog kidney exhibits a diuresis when treated with 0.54 mM 

 iodoacetate and simultaneously there is an increased CI" output, suggesting 

 an action on the normal tubular resorptive mechanisms (Ferrari and Hober, 

 1933). This was observed directly in the inhibition of phenol red transport, 

 which has been studied in greater detail by Beck and Chambers (1935), 

 Forster and Taggart (1950), and Jaffee (1954). Iodoacetate at 0.2-0.5 mM 

 retards the accumulation of phenol red and later causes a loss of what dye 

 has been accumulated, accompanied by the appearance of degenerative 

 changes in the tubules (Fig. 1-12). Although 1.1 mM iodoacetate depresses 



Fig. 1-12. Effects of iodoacetate on 



the phenol red uptake by chick nie- 



sonephros in culture. (From Beck 



and Chambers, 1935.) 



