Growth inhibition and biodegradation of catecholamines in the ciliated protozoan Tetrahymena pyriformis.
A 96-well plate culture methodology for the unicellular eukaryote Tetrahymena pyriformis, strain GL was used for the determination of toxicity and metabolism of catecholamines. Catecholamines exhibited moderate acute toxicity to Tetrahymena cells where dopamine and L-DOPA showed higher toxic potential at EC(10) (0.39 ppm and 0.63 ppm, respectively) and EC(20) (1.1 ppm and 1.0 ppm respectively) after 48 h exposure. All tested catecholamines were highly degradable in the PPY-medium due to the oxidizing environment during incubation. Also the catecholamines were naturally synthesized and released by Tetrahymena cells into the culture medium and increasingly accumulated with time where noradrenalin exhibited the highest degree of accumulation. However, the exogenous exposure of catecholamines to the cells caused the depletion of natural noradrenalin synthesis even with the addition of very low physiological concentration (0.12 ppm). Dopamine caused the higher effect on inhibiting noradrenalin synthesis. Treatment with a higher concentration (8.0 ppm) of dopamine in 96-well plates caused strong excitation of the cells and ascertained a new metabolite in vivo while the other representative catecholamines were not responsible for the production of this metabolite. This dopamine metabolite is relatively non-polar as compared to noradrenalin, adrenaline and dopamine and eluting later through the reverse phase C-18 column.
Ud-Daula
Asad
A
Helmholtz Zentrum Munchen, German Research Center for Environmental Health, Institute of Ecological Chemistry, Neuherberg, Germany.
Pfister
Gerd
G
Schramm
Karl-Werner
KW
D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D013769:Tetrahymena pyriformis / Q000254:growth & development* / Q000378:metabolism*
D002395:Catecholamines