Time course and nature of postprandial haemodynamic changes in normal man

The present study describes the nature and time course of the cardiovascular and neuro-endocrine changes that followed a standard 3100 kJ cold meal in 12 supine and fasting normal men who were studied in a balanced cross-over design. Heart rate, blood pressure, systolic time intervals and estimates of cardiac performance by impedance cardiography were measured every 10 min up to 4 h after eating. Eating caused a rapid and short-lasting increase in systolic blood pressure, estimated stroke volume and maximum velocity of impedance changes. Eating also caused a rapid and more protracted decrease in diastolic and mean blood pressure, PEP-i, QS2-i and estimated systemic vascular resistance with an increase in heart rate and estimated cardiac output. In the later phase of the profiling a drop in LVET-i was also observed. The differences vs. fasting were statistically significant and judged to be biologically relevant. Venous plasma noradrenaline rose during eating as a consequence of the postural change, but eating itself did not alter venous plasma noradrenaline, and plasma adrenaline even tended to decrease. This reflects both the roughness of venous catecholamines in estimating adrenergic changes and the complexity of the underlying mechanisms and related reflexes.