Arterial alpha-adrenergic responsiveness is decreased and SNS activity is increased in older humans

• DOI: 10.1152/ajpendo.1994.266.5.e717
• Publication Date: 2017-12-22T00:33:17Z
• Authors: R. V. Hogikyan; M. A. Supiano
• Keywords: Alpha (finance); Sympathetic nervous system; Brachial artery; Adrenergic agonist

We tested the hypotheses that 1) there is an age-associated decrease in arterial alpha-adrenergic responsiveness and 2) upregulation of this response during suppression sympathetic nervous system (SNS) activity. measured forearm blood flow (FABF) by plethysmography brachial artery infusions agonist norepinephrine (NE) nonadrenergic angiotensin II (ANG II) 15 young 14 older healthy human subjects. Among old (O) relative to (Y) we identified greater plasma NE levels (Y: 1.29 +/- 0.07 nM vs. O: 2.14 0.17 nM; P = 0.0001); a NE-mediated reduction FABF [analysis variance (ANOVA) 0.04]; and, contrast, no difference ANG II-mediated (ANOVA 0.43). In nine subjects studied guanadrel (G) suppress SNS activity, decreased [placebo (P): 2.11 0.24 G: 1.09 0.09 0.002], increased 0.01), (ANOVA: 0.69) compared with P. conclude appropriate desensitization among specific for system. homologous when activity suppressed.