SIMULTANEOUS ASSAY OF PLATELET AND PLASMA-CATECHOLAMINES BY HPLC WITH COULOMETRIC DETECTION

Platelets and monoaminergic neurons share many morphological, biochemical, and pharmacological properties. In addition to its similarities to serotonergic nerve endings, the platelet has also been considered a good model for the study of the noradrenergic function, since it can selectively take up, store, and release norepinephrine (NE). In this study platelet and plasma levels of free catecholamines (CA) in 20 healthy subjects have been determined by HPLC with a reversed phase (C18) ion-pairing system equipped with a coulometric detector. Direct correlation was observed between platelet and plasma levels of NE. A positive correlation was also found between the age of the subjects and both platelet and plasma NE levels. While showing that the peripheral noradrenergic hyperactivity of the elderly is also reflected in platelet NE content, this study also demonstrates that simultaneous assay of platelet and plasma CAs can be a useful tool for an integrated and more complete evaluation of sympathetic nervous system activity.