We compared the cardiovascular, glucose, insulin, and catecholamine responses to high-fat (F) and high-carbohydrate (C) meals in healthy young subjects (mean age 23 yr, range 19-39). Cardiac output rose 30 min after C by 32% [95% confidence interval (CI) of the increase +0.32 to +1.64 l/min] and after F by 22% [95% CI +0.30 to +1.96 l/min; P = 0.03, analysis of variance (ANOVA)]. Superior mesenteric artery blood flow rose by 87% 15 min after C (95% CI +119 to +258 ml/min) and by 122% (95% CI +138 to +392 ml/min) 45 min after F, with significantly different patterns of response (interaction effect P < 0.05, ANOVA). Calf blood flow fell and remained low for 60 min after F but only fell 15 min after C, with a return to fasting levels thereafter (interaction effect P < 0.03, ANOVA). Thirty minutes postprandially the change of calf blood flow from baseline after C was significantly different than after F (95% CI of differences +0.1 to +2.04 ml.100 ml-1.min-1). Glucose, insulin, and norepinephrine levels increased more after C than after F. Thus there are different regional vascular responses to C and F despite similar cardiac output increases.
