Abstract
A series of polyphenols have been found to reduce methylation of epinephrine and norepinephrine by O-methyl transferase in vitro, probably by acting as competitive substrates.
These substances augmented the toxicity of intravenous epinephrine in the rat, the augmented toxicity being adrenergic in nature and probably due to an increase in the life-span of epinephrine. The effects with norepinephrine were less pronounced.
The inhibitors prolonged the duration of the pressor effects of epinephrine in the spinal cat, but were less active in prolonging the effect of norepinephrine.
Pyrogallol, when given repeatedly, caused a rise in blood pressure, but this was soon followed by what appeared to be tachyphylaxis.
Pyrogallol prolonged the duration of action of endogenously released catecholamines at the nictitating membrane.
Possible explanations for the difference between epinephrine and norepinephrine are discussed.
Footnotes
- Received February 27, 1960.
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AUGMENTATION OF PHARMACOLOGICAL PROPERTIES OF CATECHOLAMINES BY O-METHYL TRANSFERASE INHIBITORS
