MITOCHONDRIA, CELLS, AND TISSUES 



583 



continued to be inhibited progressively for some time afterward at room 

 temperature, whereas at P both processes were slowed and would appear 

 to run equivalent courses. lodoacetate reached levels in the muscle about 

 1.5 times that in the medium and about half of this could be removed by 

 prolonged washing of the muscle. Thus the uptake curves presumably 

 record both reacted and free iodoacetate. It is therefore difficult to decide 

 if the penetration of the iodoacetate through the cellular membranes is 

 an important factor in the kinetics. It is perhaps safe to conclude with 



04 



IAA = 0.25mM 



-18" 



0.3 



INHIBITION - ^^-- 18" 

 OF GLYCOLYSIS ^ — "" 



-Q25 



-Ol, 



30 

 TIME (MIN) 



60 



90 



120 



150 



Fig. 12-26. Uptake of iodoacetate by frog sartorius muscle and the resulting inhi- 

 bition of glycolysis at two difierent temperatures. The solid lines represent the uptake 

 and the dotted lines the depression of the lactate formation. (From Meyerhof and 



Boy land, 1931.) 



Meyerhof and Boyland that both penetration and reaction with enzymes 

 contribute. Comparing these results with those of Lohmann (1931) on 

 muscle extracts, one would be inclined to attribute the major part of the 

 delay to the slow alkylation of the enzymes. Ghaffar (1935) investigated 

 this question by the determination of the time course of iodide release from 

 iodoacetate during the alkylation reactions in the muscle (Fig. 12-27). 

 It is evident that an appreciable inhibition of glycolysis occurred before 

 much iodide was released; in fact, after complete glycolytic block, iodide 



