The stimulation of isolated photophores (Argyropelecus) by epinephrine and norepinephrine

1. 1. Photophores isolated from the ventral region of the bathypelagic fish Argyropelecus hemigymnus respond to epinephrine and norepinephrine by a long-lasting luminescence: the maximal light emission occurring at 10 −6 M for epinephrine and 10 −5 M for norepinephrine, is estimated at 8 × 10 6 quanta/sec per photophore. 2. 2. The LD 50 value of the light response calculated from the dose-response curves to both neuromediators, is 2 × 10 −7 M for epinephrine and 2 × 10 −6 M for norepinephrine. 3. 3. The light response to epinephrine is depressed by propranol and phentolamine 10 −5 M, and the maximum is shifted to concentration higher than 10 −6 M. Phentolamine completely blocks the light evoked by norepinephrine at a concentration lower than 10 −5 M and shifts the light maximum to 10 −3 M. 4. 4. Photophores show a greenish fluorescence when excited with 365 nm u.v. light; the fluorescence intensity, is largely decreased after the light emission.