Relationship of blood pressure, heart rate and behavioral mood state to norepinephrine kinetics in younger and older men following caffeine ingestion

Objective: To examine age-related differences in blood pressure, heart rate, behavioral mood state and norepinephrine kinetics after caffeine ingestion in younger and older men. Design: Placebo-controlled, double-blind study. Setting: General Clinical Research Center, University of Vermont. Subjects: 10 older (O) (65–80 y) and 10 younger (Y) (19–26 y) healthy men who were moderate consumers of caffeine (Y=126±30 mg/d; O=160±44 mg/d:NS; mean±s.e.m.). Intervention: All volunteers were characterized for fasting plasma glucose, insulin and caffeine levels, body composition, anthropometry, physical activity, and energy intake. Before and after placebo and caffeine ingestion (5 mg/kg fat-free mass) test days, the following variables were measured in all subjects: heart rate, blood pressure, mood state, and norepinephrine concentrations (NEconc), appearance (NEapp) and clearance (NEcl). Main outcome measures: Systolic and diastolic blood pressure, heart rate, mood state, and norepinephrine kinetic responses to placebo and caffeine ingestion. Results: Following caffeine ingestion, plasma caffeine levels were similar in Y and O men. Systolic (SBP) and diastolic (DBP) blood pressure increased significantly (P