Respiratory changes associated with the in vitro evagination of Taenia solium cysticerci

The metabolic adaptability of Taenia solium cysticerci was studied in vitro, by measuring their respiratory rate before, during, and after trypsin-induced evagination. Under aerobic conditions, the oxygen consumption increased about 40% during evagination of the cysticeri and returned to basal rates after the process was completed. The percentage of evagination induced by trypsin was not affected under anaerobic conditions or in the presence of respiratory poisons such as cyanide and carbon monoxide. These data indicate that cysticerci use either aerobic or anaerobic pathways according to oxygen availability in the environment. Results from experiments of irreversible respiratory poisoning using cyanide suggest the presence of an alternative respiratory chain. Proteolytic action of trypsin on a fibrous layer surrounding the invaginated larvae is suggested by histological evidence.