Evidence for presynaptic beta-adrenoceptor stimulation 24 hours after a 6 hour adrenaline infusion

1. The effects of 6 h infusions of adrenaline (INF-A) and dextrose (INF-D) were compared in nine normal subjects. 2. A significant increase in systolic blood pressure was observed during INF-A compared with INF-D and, 24 h after infusion, diastolic blood pressure was higher after INF-A than after INF-D. 3. Heart rate (HR) was significantly higher during INF-A than during INF-D. 4. As expected, plasma ADR increased significantly during INF-A but, unexpectedly, remained elevated 60 min post infusion compared with INF-D. Levels during activity the next morning were somewhat higher after INF-A, but not significantly different from INF-D. 5. Plasma NA increased transiently during INF-A and decreased during INF-D. Urinary NA was significantly higher during INF-A than during INF-D, and insignificantly higher during overnight recumbency, consistent with enhanced noradrenergic transmission.