1888
Experiments on narcotized cats demonstrated that the derivatives of 2 - mercaptobenzimidazole possessing the properties of specific bradycardic agents and coded as CM - 251 , CM - 266 , and CM - 345 , reduce the mean rise of segment ST on numerous leads of the epicardial electrogram during 5 - min occlusion of the anterior descending branch of the left coronary artery .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 None