A carbohydrate meal attenuates the forearm vasoconstrictor response to lower body subatmospheric pressure in healthy young adults.

The cardiovascular (CV) responses to meal ingestion and orthostasis are well established. The effect of meal ingestion and meal composition on the CV responses to orthostasis are unknown. The effect of high carbohydrate (HC) and high fat (HF) meal ingestion on the CV responses to simulated orthostatic stress (using graded lower body subatmospheric pressure (LBSP)) was assessed in nine healthy young volunteers. Cardiac output (CO), forearm blood flow (FABF) heart rate (HR) and blood pressure (BP) were measured before and during LBSP while fasted and after eating HC and HF meals. Ingestion of both meals led to an increase in CO and HR. Both meals resulted in a fall in total peripheral resistance but only HC led to a significant fall in BP (p < 0.05). HF had no effect on the CV responses to LBSP, whereas HC resulted in attenuated FABF and forearm vascular resistance responses (p < 0.05). Thus, ingestion of an HC meal significantly attenuates the forearm vascular response to orthostatic stress and the hypotensive effect of orthostasis is additive to that occurring after an HC meal.