To avoid some of the disadvantages associated with using radiolabeling to investigate adenyl purine content and release from excitable tissues, a reverse-phase high-pressure liquid chromatographic method utilizing fluorescence detection for the measurement of picomole amounts of endogenous ATP and its 6-amino purine analogs has been developed. This procedure has been used to determine the content of adenyl purines in the guinea pig vas deferens and that released from the tissue following stimulation of adrenergic nerves. The total tissue content was measured to be 1.6, 0.76, and 0.10 mumol/g of ATP, ADP, and AMP, respectively. However, adenosine could not be detected. Hypoxia caused a significant decrease in ATP content concomitant with an increase in adenosine content to 0.04 mumol/g. Following transmural electrical stimulation of the guniea pig vas deferens, the release of the following purine compounds was detected: ATP (0.106 nmol/g), ADP (0.242 nmol/g), AMP (0.035 nmol/g), and adenosine (0.454 nmol/g).