PLASMA ENDOTHELIN-1 CONCENTRATIONS IN PATIENTS WITH RETINAL VEIN OCCLUSIONS

Aims-To investigate whether plasma levels of endothelin-1 (ET-1), a po tent vasoconstricting peptide that is crucial in regulating retinal bl ood flow, were elevated in patients with retinal vein occlusion (RVO). Methods-ET-1 plasma concentrations were determined by radioimmunoassa ys in a double blind fashion in a group of 18 selected patients with R VO, in 20 healthy age matched non-smoking, normoglycaemic, normotensiv e control subjects, and in 15 patients with uncomplicated essential hy pertension in the same age range.Results-Patients with RVO had signifi cantly increased ET-1 plasma levels (14.22 (SD 4.6) pg/ml) compared wi th both normal subjects (7.90 (1.6) pg/ml; p < 0.05) and hypertensive patients (8.50 (2.9) pg/ml; p < 0.05), The highest concentrations of c irculating ET-1 were found in patients with RVO of the ischaemic type (16.97 (3.5) pg/ml; p < 0.01; n = 7). Systemic hypertension alone did not account for the observed increase in plasma ET-I concentrations. C onclusions-These findings raise the possibility that the increased cir culating ET-1 levels in patients with RVO may be a marker of the occlu sive event, thereby suggesting that ET-1 homeostasis may be relevant t o RVO pathogenesis and retinal ischaemic manifestations.