The respiratory behavior of Lewis carcinoma cells--existence of a cyanide-resistant respiration.

: The respiratory O2 consumption of vegetative, non-necrotic, Lewis lung carcinoma cells was found to be very low compared with that of non-tumor tissues and was highly resistant to cyanide. However, the resistant rate was inhibited by salicylhydroxamic acid (SHAM) in either isolated cells or tissue fragments. In addition, this compound did not affect their cytochrome-c oxidase activity. The results support the existence of an alternative oxidase system that significantly contributes to oxygen uptake in Lewis carcinoma cells. To our knowledge, this is the first report showing significant SHAM-sensitivity of tumor respiration and perhaps of higher animal cell respiration.