Adrenergic control of luminescence and cellular metabolism in Porichthys isolated luminous organs

Abstract

1. Isolated photophores from the luminous fish Porichthys produce light in response to adrenaline and the metabolic inhibitors iodoacetic acid (IAA) or potassium cyanide (KCN). 2. We attempted to analyse the interactions of cellular metabolism and adrenergic stimulation of the photogenic cells. 3. Photophores were treated with IAA in the presence of pyruvate. In these conditions, IAA does inhibit glycolysis without inducing any luminescent activity of the cells. 4. Similarly, other photophores were incubated with KCN in the presence of glucose, in order to inhibit cellular respiration while keeping the luminous system inactive. 5. We observed that adrenergic stimulation of these photophores remained effective and induced a light emission, demonstrating that glycolytic and oxidative metabolism are not absolutely essential to the mechanism underlying adrenergic activation of the luminous system. 6. The comparison of these luminescences with adrenergic responses of control photophores showed that the light emission to adrenaline was markedly inhibited by glycolysis blockade but potentiated by an inhibition of cellular respiration. 7. As the inhibitory effect of IAA does not result from a direct action of IAA on the luminous system, these results suggest that adrenaline activation of adrenergic receptors might interact with glycolysis in photogenic cells. 8. Glyceraldehyde 3-phosphate, or some derivatives, could be implicated in the glycolytic control of luminescence in the photophores.