Effects of bronchodilatation with salmeterol on the autonomic nervous system

Abstract: Neurohumoral activation is present in COPD and might provide a link between pulmonary and systemic effects, especially cardiovascular disease. Because long acting inhaled β-agonists reduce hyperinflation, they could reduce sympathoexcitation by improving the inflation reflex. We aimed to evaluate if inhaled therapy with salmeterol reduces muscle sympathetic nerve activity (MSNA) evaluated by microneurography. Methods: MSNA, heart rate, blood pressure, and respiration were continually measured as placebo and salmeterol (50 μg) were inhaled sequentially. Following 4 weeks of treatment with salmeterol 50 μg twice daily, measurements were repeated without placebo administration. Results: A total of 32 COPD patients were included. Valid MSNA signals were obtained from 18 patients. Change in MSNA (bursts/100 heart beats) following acute administration of salmeterol did not differ significantly from the change following placebo (-1.96 ± 9.81 vs. -0.65 ± 9.07; p=0.51) although hyperinflation was significantly reduced. Likewise, no changes in MSNA or catecholamines were observed after 4 weeks. Salmeterol treatment was safe and well tolerated. Conclusions: By using microneurography as a gold standard to evaluate sympathetic activity we found no change in MSNA following salmeterol inhalation. Thus, despite an attenuation of hyperinflation, the long acting β-agonist salmeterol does not appear to reduce nor incite sympathoexcitation.2015-06-2