A KINETIC MODEL FOR THE STUDY OF THE DISPOSITION OF CIRCULATING NOREPINEPHRINE

¹ Illinois State Psychiatric Institute, Chicago, Illinois

A kinetic model relevant to the disposition of circulating norepinephrine (NE) is presented. It is noted that in such a system when labeled NE is placed in plasma as a pulse or infusion the plot over time representing the appearance or disappearance of the tagged NE in plasma or urine will be biphasic and as such cannot be taken as evidence for the existence of two turnover times of the endogenous or unlabeled NE. Similarly, it is to be expected that the introduction of tagged NE into plasma will result in differences in the specific activities of the various NE pools. A correct kinetic description of the disposition of circulating NE can be best gained by solving for the fractional rate constants of the model. A method of solution is presented and the assumptions of the approach used are discussed.