The Relationship of Epinephrine Oxidation to Rat Parotid Metabolism and Secretion in Vitro 1

Abstract

Summary

Epinephrine conversion to ad-renochrome by rat parotid in vitro was verified by the appearance of a pink color in the medium and an increase in UV absorbance. Preincubation with epinephrine to increase adrenochrome concentration during incubation produced no alteration in the magnitude of catecholamine stimulation of glucose-6-¹⁴C oxidation. Inhibition of epinephrine conversion to adrenochrome or of degradation by monamine oxidase also had no effect on the response to this catecholamine. Although epinephrine produced pronounced stimulation of α-amylase secretion, glucose-6-¹⁴C oxidation, leucine-U-¹⁴C oxidation, and inhibition of leucine-U-¹⁴C incorporation into rat parotid protein, no measurable effects were produced by adrenochrome. The present results strongly indicate that epinephrine rather than adrenochrome or other oxidation products is primarily responsible for the alterations in α-amylase secretion and metabolism observed with rat parotid in vitro.