EFFECTS ON SKELETAL MUSCLE 197 



rigor occurs. Lundsgaard (1930 a, d) emphasized that during treatment with 

 iodoacetate, at a time when lactate formation is blocked but before con- 

 tracture has begun, contractions may be quite normal, indicating the unim- 

 portance of lactate for the contraction. Furthermore, the over-all configura- 

 tion of the contraction — latent period, duration of contraction, and max- 



FiG. 1-14. General pattern of muscle response to iodoacetate, 



showing; lag period, slow contractile depression, and eventual 



contracture. 



imal tension — is not changed by glycolytic block.* (Henriques and Lunds- 

 gaard, 1931). The phenomenon of treppe is not only evident in poisoned 

 muscles but may be even more pronounced (Lindenbergh, 1932; Lippay 

 and Patzl, 1935). A comparison of normal and iodoacetate-treated frog 

 muscle is shown in Fig. 1-15. Iodoacetate somewhat prolongs the relaxation 



NORMAL IODOACETATE - TREATED 



Fig. 1-15. Effect of iodoacetate on the treppe phenomenon 

 in frog gastrocnemius muscle. (From Lippay and Patzl, 1935.) 



following electrical stimulation of diaphragm (Kuschinsky and Liillmann, 

 1954), and yet reduces or abolishes the prolongation of contraction induced 

 by veratrine (Martensson, 1935). The increased treppe may be only an ex- 

 pression of the developing contracture. The magnitude of the postrest con- 

 traction seems to be slightly reduced. 



* The contractile tension will eventually decrease, of course, at a rate depending 

 on many factors, but the point here is that normal contractions can occur at a time 

 when the EM pathway is markedly inhibited. 



