Systemic overperfusion and resting blood pressure.

During psychosocial stressors, individuals with mildly elevated resting blood pressures (BP) exhibit cardiac output (CO) that is in excess of metabolic demand (i.e., systemic overperfusion). The present study used the "additional" CO method to assess whether individuals in the high average BP range also exhibit systemic overperfusion at rest. Healthy young adult males (N = 48), divided into "high average" and "low average" groups using resting BP, participated in an active coping task. Consistent with past research, the high average group evidenced higher levels of additional CO than did the low average group during both baseline and task periods. More importantly, the high average group also exhibited significant amounts of additional CO at rest, whereas the low average group did not. These results may help to advance our understanding of the process by which systemic overperfusion may contribute to the development of elevated BP.

Defensive hostility and anger expression: relationship to additional heart rate reactivity during active coping.

The main purpose of the present study was twofold: (a) to assess the relationship between defensive hostility (high hostility/high defensiveness) and additional heart rate reactivity during active coping and (b) to determine if the construct of anger-out might lend additional sensitivity to the predictive power of the defensive hostility model. Forty individuals were randomly assigned to complete a mental arithmetic task with or without the threat of shock. Participants also completed the Cook-Medley Hostility Inventory (Ho), the Marlowe-Crowne Social Desirability Scale (MC), and the Spielberger Anger Expression Scale. Defensive hostile subjects (high Ho/high MC) were significantly more reactive than any other subgroup. In addition, the combination of low Ho/high anger-out scores yielded a subgroup significantly less reactive than any other subgroup. These findings clarify the complex relationship of hostility and cardiovascular reactivity.

A comparison of biofeedback-assisted cardiodeceleration in type A and B men: modification of stress-associated cardiopulmonary and hemodynamic adjustments.

The primary purpose of this experiment was to examine the cardiac effects of instructions and biofeedback to reduce heart rate during both rest and a behavioral stressor. A second purpose was to assess respiratory, hemodynamic, and metabolic function in conjunction with heart rate. A final aim was to compare the effects of biofeedback on Type A and B men. Type A subjects fell in the upper 10% of the distribution of Jenkin's Activity Survey scores and Type B subjects fell in the lower 10%. Subjects experienced one of three instructional sets during an initial session: instructions to reduce heart rate with biofeedback; instructions to reduce heart rate without biofeedback; and instructions to sit quietly. During a second session, all subjects received identical instructions prior to the behavioral stressor. Heart rate, pulmonary gas exchange, and ventilation were measured breath-by-breath. During the first session, the groups did not differ in any measured parameter, but Type As had higher heart rates than did Type Bs across all conditions. During the second session, subjects given instructions to reduce heart rate with and without biofeedback did not differ in heart rate; as expected, however, both of these groups had smaller increases in heart rate than did the control group. Interestingly, the tachycardia of the control group occurred without an increase in oxygen consumption, indicating a cardiac-metabolic dissociation in this group. The modification of heart rate without a concomitant change in metabolism is important in understanding the association between cardiac and metabolic function.

Hemodynamic and metabolic adjustments during exercise and shock avoidance in dogs.

The purpose of this study was to examine whether the hemodynamic and metabolic consequences of a physical (treadmill excercise) and behavioral (signaled shock-avoidance) stressor could be differentiated. To do this, direct continuous recordings of cardiac output, systolic and diastolic blood pressure, and discrete determinations of the arterial-mixed venous oxygen ((a-v)O2) content difference were analyzed in six dogs during exposure to three grades of treadmill exercise and when working on a shock-avoidance task. The results indicated that in five animals the relationship between cardiac output and the (a-v)O2 difference during shock-avoidance conditioning was significantly different from the corresponding pattern observed during exercise. In four animals the data suggested that avoidance conditioning, relative to exercise stress, elicited overperfusion. Behavioral stress also produced reliable elevations in diastolic and systolic blood pressure. These results suggest that, when compared to physical stress, behavioral stress can produce a dissociation of cardiovascular and metabolic processes in the presence of acute pressor responses.