Summary
Background: Contradictory results on plasma endothelin-1 (ET-1) levels in patients with rheumatoid arthritis have been reported in previous studies. We therefore evaluated whether plasma ET-1 levels in patients with rheumatoid arthritis differ from those of normal controls. Since systemically increased levels of ET-1 are known to occur in tandem with primary or secondary vascular dysregulation, we also measured peripheral blood flow by means of nailfold capillaroscopy
combined with a cold provocation test.
Material/Methods: We measured plasma levels of ET-1 in twelve patients with different stages of rheumatoid arthritis by means of a specific radioimmunoassay, and compared ET-1 values to those of
healthy controls. Capillary blood flow and the frequency of cold-induced vasospasm were studied in parallel, using nailfold capillaroscopy combined with a cold provocation test.
Results: Plasma ET-1 levels were significantly increased in patients with rheumatoid arthritis (p = 0.01) when compared to controls (2.38±0.95 pg/ml vs. 1.53±0.38 pg/ml). Capillary blood flow
was reduced when compared to our own normal values, and a cold-induced blood standstill was seen in 58% of the patients.
Conclusion: Patients with rheumatoid arthritis exhibit significantly elevated levels of ET-1, which may be associated with the symptoms of vascular dysregulation observed in nailfold capillaroscopy.
Even though the clinical conclusions should be drawn from this study with caution, additional therapy with calcium channel blockers or, possibly in the future, with ET-1 receptor blockers, may be beneficial in patients with rheumatoid arthritis.

Keywords: Arthritis, Rheumatoid - blood, Arthritis, Rheumatoid - pathology, Case-Control Studies, Endothelin-1 - blood, Microscopic Angioscopy, Radioimmunoassay, Regional Blood Flow, Time Factors