Cardiovascular response to stress.

The behavioral characteristics of psychological stressors have been operationally defined. A psychological stressor is one that causes a stress response in a predictable percentage of index subjects. However, it may not always produce a stress response, and the probability of producing such a response depends on interactions between the behavioral situation and the individual involved. Thus there is a danger that a psychological stressor will be defined according to the stress response it causes rather than its structural characteristics. The characteristics that enhance the likelihood that a psychological stressor will cause a stress response are its novel, challenging, or threatening aspects that engage a subject in continuous active mental effort. The intensity of the stress response depends on the intensity of mental effort exerted to meet a challenging situation, whether or not that situation is perceived as threatening. The behavioral response to a psychological stressor also has been defined. It includes somatomotor, neuroendocrine, and cardiovascular components. The somatomotor response to stressful psychological events includes purposeful active coping to counter the challenge or threat posed by the stressor. The neuroendocrine response includes a combination of pituitary-adrenal cortical and hypothalamic-sympathetic-adrenal medullary secretions. The cardiovascular response includes a combination of increased rate and force of cardiac contraction, skeletal muscle vasodilation, venoconstriction, splanchnic vasoconstriction, renal vasoconstriction, and decreased renal excretion of sodium. Of all the modifiers that influence the stress response to a psychological stressor, family history is the one most likely to have an effect. A family history of essential hypertension increases the likelihood that a subject will respond to a psychological stressor with a cardiovascular stress response pattern. Other predisposing characteristics that increase the likelihood of a stress response include behavioral patterns of response to challenge or threat but may also include anatomic or biochemical characteristics that increase susceptibility to neurogenic activation of central aminergic mechanisms.