Accumulation of radioactivity after repeated infusion of 3H-adrenaline and 3H-noradrenaline in the rat as a model animal

• We administered repeatedly 3H-adrenaline and 3H-noradrenaline i.v.
• We provide basic knowledge about the distribution of catecholamines or their adducts in the body.
• Half-life of rat serum albumin was not affected by catecholamination.
• Catecholamines (adducts) accumulated in the hair.
• Catecholamines (adducts) in hair might be used for evaluating long term stress.

Besides enzymatic inactivation, catecholamines bind non-enzymatically and irreversible to proteins. The physiological impact of these catecholamine adducts is still unclear. We therefore collected basic data about the distribution of catecholamine adducts in the rat after repeated intravenous administration of 3H-adrenaline and 3H-noradrenaline.In all animals radioactivity in blood increased until the last injection on Day 7 and decreased then slowly close to background values (plasma) or remained higher (erythrocytes). In all sampled tissues radioactivity could be found, but only in hair high amounts remained present even after 3 weeks. Half-life of rat serum albumin loaded with 3H-adrenaline or 3H-noradrenaline was not altered.This study provides basic knowledge about the distribution of catecholamines or their adducts, but physiological effects could not be demonstrated. However, for the first time deposition and accumulation of catecholamines (adducts) in the hair could be proven, suggesting that hair might be used for evaluating long term stress.