The influence of acute starvation on the cardiovascular responses to lower body subatmospheric pressure or to standing in man

Abstract

The cardiovascular responses to lower body subatmospheric pressure or to standing were measured in the same nine normal male subjects after a 12 h and after a 48 h fast. After the 48 h fast there was a significant reduction in diastolic blood pressure and forearm vascular resistance (relative to the values after a 12 h fast) when subjects were supine. During exposure to lower body subatmospheric pressure, subjects who had fasted for 48 h showed an inability to maintain systolic blood pressure, accompanied by an impairment of forearm vasoconstriction and an exaggerated tachycardia (relative to their responses after a 12 h fast). Similar disorders of cardiovascular homoeostasis were seen on standing. The results are consistent with an inhibition of sympathetic nervous activity after a 48 h fast, but other possibilities are discussed.