Plasma catecholamines and hemodynamic responses to stress states in man

The relationship between the plasma catecholamine and hemodynamic responses to stress in man was studied using radionuclide left ventricular angiography to assess changes in cardiac volumes. In 10 healthy men, the maximum plasma norepinephrine (NE) and epinephrine (EPI) responses to symptom-limited supine bicycle exercise were considerably greater than the responses to isometric handgrip exercise or to a cold pressor test. Similarly, increases in heart rate, systolic blood pressure, stroke volume, ejection fraction, and cardiac output were greatest with bicycle exercise. Both the plasma catecholamine and hemodynamic responses to handgrip exercise tended to be intermediate, and the smallest responses were observed during cold pressure testing. The plasma NE and EPI responses to symptom-limited upright treadmill exercise in another group of 10 men were greater than the responses to supine bicycle exercise. During bicycle exercise and during handgrip exercise there were significant correlations between plasma NE and EPI levels and changes of heart rate, blood pressure, and cardiac output. In addition, when data from all three stresses were combined and effects of heart rate and subject differences were controlled for, plasma NE and EPI levels were significantly correlated with ejection fraction. These findings suggest that release of EPI and NE during stress states may contribute to some of the hemodynamic responses that occur during stress.