Izzo J L, Larrabee P S, Sander E, Lillis L M
Department of Medicine, University of Rochester School of Medicine and Dentistry, New York.
Am J Hypertens. 1990 May;3(5 Pt 1):405-7. doi: 10.1093/ajh/3.5.405.
To investigate the possibility that seasonal adaptation requires significant hemodynamic changes, 5 normotensive and 21 mildly hypertensive subjects were followed through 4 seasons for changes in systemic hemodynamics and sympathetic nervous activity. In the upright position wintertime blood pressures increased by 3% (P = NS) over summer values whereas cardiac output and stroke volume decreased by 18% and 21%, respectively (P less than .0017 for each). Similarly, wintertime upright heart rate increased by 7% (P less than .017) with larger parallel increases in systemic vascular resistance (+24%, P less than .0017) and plasma norepinephrine (+26%, P less than .017). The supine values followed similar trends but the magnitude of changes was about 50% less than the corresponding upright values. Thus, in the northern US, wintertime vasoconstriction is related to increased sympathetic nervous activity and decreased cardiac output. When these reciprocal changes are proportional, blood pressure remains constant.
为了研究季节性适应是否需要显著的血流动力学变化，对5名血压正常者和21名轻度高血压患者进行了为期4个季节的跟踪，观察其全身血流动力学和交感神经活动的变化。在直立位时，冬季血压较夏季升高3%（P=无显著性差异），而心输出量和每搏输出量分别下降18%和21%（每项P<0.0017）。同样，冬季直立位心率升高7%（P<0.017），同时全身血管阻力（+24%，P<0.0017）和血浆去甲肾上腺素（+26%，P<0.017）也有较大幅度的平行升高。仰卧位数值也呈现类似趋势，但变化幅度比相应的直立位数值小约50%。因此，在美国北部，冬季血管收缩与交感神经活动增加和心输出量减少有关。当这些相反的变化成比例时，血压保持恒定。
