Original Papers: PDF OnlyStruthers Allan D.; Pai, Sudha; Seidelin, Peter H.; Coutie, Wendy J.R.; Morton, James J.Journal of Hypertension: December 1987 - p 671-676 Buy Abstract Much animal evidence exists to suggest that there is an interaction between noradrenaline (NA) and angiotensin II (All). We have now sought evidence for a postsynaptic All/NA interaction. Ten normotensive volunteers were infused with dextrose/saline, All/saline, dextrose/NA or All/NA in a randomized single-blind fashion. The respective increases in systolic blood pressure (SBP) were -4 ± 6, -2 ± 9, 4 ± 6 and 14 ± 16 mmHg at comparative time intervals while the corresponding increases in diastolic blood pressure (DBP) were 2 ± 4, 6 ± 7, 9 ± 6 and 14 ± 8 mmHg. ANOVA confirmed that All and NA had a synergistic interaction (P< 0.05) in elevating SBP while there was merely an additive effect in elevating DBP. Plasma NA and All levels were unchanged by the coincidental presence of All and NA, respectively, which excludes a generalized pharmacokinetic interaction between All and NA. This study provides evidence for a postsynaptic All/NA interaction with regard to SBP but not DBP although the precise location of this interaction remains uncertain. Therefore, in considering the pathogenesis of SBP abnormalities, concomitant measurements of both NA and All may be important. © Lippincott-Raven Publishers.