LYSOSOMES, A NEW CROUP OF CYTOPLASMIC PARTICLES 



153 



40 



MEAN UNSEDIMENTABLE ACTIVITY 

 % OF TOTAL o 



LIGATED LOBE 



UNLIGATED LOBE 



'• — - — — —_ 



HOURS AFTER LIGATION 



24 



48 



Fig. 12. Release of lysosomal enzymes in ischemic liver lobe. Same experiments as figure 11. 

 Each point represents the mean for three animals nf the averages of the unsedimentable 

 activities of acid phosphatase, cathepsin and acid ribonuclease and deoxyribonuclcase. The 

 unsedimentable activity of /3-glucuronidase follows the same course during the first 6 hours 

 and then exhibits a sccontl increase coincident with an unexplained increase in total activity. 



specific activities of the lysosomal enzymes were notably increased, showing, 

 therefore, that these enzymes had participated to only a small extent in the pro- 

 tein loss. Finally, the tmsedimentable activities of these enzymes were increased 

 almost as much as after ligation of the vascular pedicle and they could therefore 

 be taken as being largely in free form. This biochemical picture, which is repre- 

 sented diagrammatically in figure 13. was exactly that which might be expected 

 for an organ in the process of being digested by its own lysosomes. 



The changes observed in the animals treated with carcinogenic dyes were very 

 complex and have been described in detail (28, 20). The most significant ones 

 were an increase in total cathepsin and acid nucleases and in the free or un- 

 sedimentable activities of all lysosomal enzymes in the precancerous livers and in 

 the tumors. 



The investigations summarized above have established a strong correlation 

 between the intensity of necrotic phenomena and the proportion of lysosomal 

 enzymes found in free or unsedimentable form in the homogenized tissue. 



