Light K C, Sherwood A
Department of Psychiatry, University of North Carolina, Chapel Hill 27599-7175.
Health Psychol. 1989;8(5):577-95. doi: 10.1037//0278-6133.8.5.577.
Blood pressure (BP) and hemodynamic responses (cardiac output [CO] and total peripheral resistance [TPR]) to a competitive reaction-time task, previously shown to increase beta-adrenergic activity, were compared in 20 Black and 20 White young men, once following infusion of saline placebo and later repeated after infusion of the nonselective beta-antagonist, propranolol. Both racial groups included subjects with marginal systolic BP (SBP) elevations (n = 6 Whites, n = 5 Blacks) and subjects with normal BP (n = 14 Whites, n = 15 Blacks). Blacks with marginal SBP elevations showed greater diastolic BP increases during the stressor than their White counterparts, both before and after beta-blockade. Both Blacks and Whites with marginal SBP elevations showed greater CO increases during the task than normotensives prior to blockade. Independent of BP status, Black subjects consistently showed higher TPR responses to the task than Whites (lesser decreases before blockade and greater increases after blockade). Blacks also showed greater diminution than Whites after blockade in ionotropic myocardial responses (stroke volume, pre-ejection period, and CO) to the stressor. The possible contributions of alpha-adrenergic and beta-adrenergic influences to these racial group differences are discussed.
在20名黑人青年男性和20名白人青年男性中，比较了他们在一项竞争性反应时任务中的血压（BP）和血流动力学反应（心输出量[CO]和总外周阻力[TPR]），该任务先前已证明会增加β-肾上腺素能活性。在输注生理盐水安慰剂后进行了一次测量，随后在输注非选择性β-拮抗剂普萘洛尔后再次进行测量。两个种族组均包括收缩压（SBP）略有升高的受试者（白人6名，黑人5名）和血压正常的受试者（白人14名，黑人15名）。在β受体阻滞剂治疗前后，SBP略有升高的黑人在应激源作用期间的舒张压升高幅度均大于其白人对应者。在阻断前，SBP略有升高的黑人和白人在任务期间的心输出量增加幅度均大于血压正常者。与血压状态无关，黑人受试者对该任务的TPR反应始终高于白人（阻断前下降幅度较小，阻断后升高幅度较大）。在阻断后，黑人在应激源作用下的心肌收缩反应（每搏输出量、射血前期和心输出量）的降低幅度也大于白人。讨论了α-肾上腺素能和β-肾上腺素能影响对这些种族差异的可能作用。
