Effects of Adrenalin on the Oxygen Consumption and Luminescence of the Photophores of the Mesopelagic Fish Argyropelecus Hemigymnus

1. Photophores isolated from the mesopelagic fish Argyropelecus hemigymnus consume oxygen at a rate of l.22 ± 0.17 nmol min−1 in saline at 20°C. 2. In the presence of 5 × 10−4 moll−1 adrenalin the preparations that responded by a long-lasting luminescence showed a significant decrease of their resting respiration rate. After the adrenalin had been washed out, oxygen consumption increased immediately to the previous resting level and was inhibited by 5 × 10−4moll−1 KCN. 3. It is suggested that the mechanism of light production by isolated photophores of the epipelagic fish Porichthys and the mesopelagic fish Argyropelecus are different.