Adsorption of Catecholamines on a Gold Electrode Surface Studied by Specular Reflection Measurement

Abstract

The adsorption of catecholamines including norepinephrine, epinephrine, isoproterenol, dopamine, dopa and homocatechol on a gold electrode surface was studied in phosphate buffer of pH 6.9 by specular reflection measurement. Norepinephrine is oxidized at potentials more positive than +0.1 V vs. saturated calomel electrode (SCE) and adsorbed at the potential range from-0.7 to-0.05 V. Its antagonists, phenoxybenzamine, tolazoline, ergotamine, oxprenolol and propranolol, are also adsorbed on the electrode, more strongly than norepinephrine. The adsorption behavior of catecholamines on the electrode surface may reflect electrostatic interactions between adrenergic transmitter substances and their receptors.