IL6 and rheumatoid arthritis: 1984; Barretto et al. 2009). Experimental data from animals showing that inflammatory cytokines (IL‐6, TNF‐α, IL‐1β) can increase sympathetic nerve activity (Niijima et al. 1991; Zhang et al. 2003; Helwig et al. 2008) led to our hypothesis that an elevated circulating cytokine concentration is associated with increased MSNA in RA. By using microneurography to provide a direct assessment of sympathetic outflow, we circumvented the limitations associated with the measurement of plasma catecholamines, which reflect tissue clearance and uptake, as well as production (Esler et al. 1990).