ET-1 plasma levels during cold stress test in sclerodermic patients

Endothelial cell injury in blood vessels of small arteries and capillaries is considered the primary event in the pathogenesis of systemic sclerosis (SSc). Because endothelin-1 (ET-1) is mainly released in the site of endothelial cell damage, thereby inducing a potent vasoconstriction, it was our intention to study ET-1 release in a group of SSc patients during a cold pressor test (CPT). Twelve SSc patients and a control group of 10 healthy subjects underwent CPT. Blood samples for ET-1 assay were collected at 90 and 180 seconds of exposure to cold stress. Heart rate and blood pressure were recorded at the same intervals. A capillaroscopic examination was performed in both groups before and after CPT. We observed significantly higher levels of plasma ET-1 in SSc patients compared with those of the control group at baseline (P=0.007) and at 90 (P=0.006) and 180 seconds (P=0.03) of CPT. During the test, the capillaroscopic examination showed a dramatic worsening of the vascular picture that was parallel to the increase in ET-1 plasma levels. This suggests that higher ET-1 plasma levels can have a part in the acute vascular reactivity of SSc patients undergoing CPT.