ABSTRACT
Basal oxygen consumption of isolated photophores from Porichthys sp. at rest, i.e. without light emission, increased significantly from 0.101±0.021nmolmin−1 to 0.173±0.016nmolmin−1 in response to the addition of 5.5mmol l−1 glucose.
5.5mmol l−1 glucose pretreatment modified the time course of the two phases of adrenaline-induced luminescence; an increase in oxygen consumption was observed during the fast phase of light production but a decrease occurred during the slow phase of luminescence.
Pretreatment of isolated photophores with 5.5mmol l−1 glucose totally inhibited the light emission induced by 1mmol l-1 potassium cyanide. With this treatment, the respiration rate decreased progressively and after 40min reached a value not significantly different from zero.
Even after blockage of cellular respiration by cyanide, an increase in the rate of oxygen consumption was observed during the fast adrenaline-induced luminescence.
Glucose utilisation by glycolysis or by oxidative metabolism may provide energy to an inhibitory mechanism that maintains the photophores in a non-luminescent state.
We suggest that the oxygen consumed during the fast phase of adrenaline luminescence could represent the activity of an extramitochondrial oxidative pathway involved in the light reaction.
