Routine high-performance liquid chromatographic determination of myocardial interstitial norepinephrine

The present study describes a high-performance liquid chromatographic-electrochemical detection (HPLC-ED) system for routine measurement of the low levels of norepinephrine (NE) found in the myocardial interstitial space. In this system, an in vivo detection limit of 100 fg in a 50-microliters injection was achieved for NE. Using cardiac dialysis technique, 20-microliters dialysates were sampled from the myocardial interstitial space at 2-min intervals. The basal dialysate NE concentration was 16.6 +/- 4.0 pg/ml. This low detection limit allowed the dialysate NE concentration to be monitored for dysfunction of the cardiac sympathetic nerve terminal. This system offers a new possibility for routine analysis of myocardial interstitial NE levels.