Endothelin-1 plasma levels in normal-tension glaucoma: abnormal response to postural changes.
BACKGROUND
Endothelin-1 (ET-1) is a potent vasoconstrictor peptide produced by vascular endothelial cells. ET-1 may have a role in the pathogenesis of various vascular diseases. There are reports in the literature that ET-1 plasma levels are raised in normal-tension glaucoma (NTG) patients.


METHODS
ET-1 concentration, plasma renin activity, and 24-h blood pressure were measured in 21 high-tension glaucoma (HTG) patients, 19 NTG patients, and 20 non-glaucomatous controls in supine and upright positions.


RESULTS
ET-1 plasma levels tended to be higher in NTG patients (3.2 +/- 2.2 pg/ml) than in HTG patients (2.2 +/- 0.6 pg/ml) and controls (2.6 +/- 0.7 pg/ml). The differences, however, were not statistically significant. The individual scatter was significantly greater in the NTG group, indicating that our NTG patients are a heterogeneous population. The physiological increase in ET-1 plasma level after changing from the supine to the upright position was absent in NTG patients. Plasma renin activities tended to be lower in NTG patients (1.2 +/- 1.2 ng/ml/h) than in HTG patients (1.3 +/- 0.8 ng/ml/h) and controls (2.0 +/- 1.7 ng/ml/h). This may explain why NTG patients had relatively low blood pressure despite high ET-1 levels.


CONCLUSIONS
Our data support the hypothesis that vascular dysfunction may be involved in the pathogenesis of optic nerve damage in normal-tension glaucoma.
University Eye Clinic, Basel, Switzerland.
H J
HJ
Kaiser
J
J
Flammer
M
M
Wenk
T
T
Lüscher
D001794:Blood Pressure; D016232:Endothelins / Q000097:blood*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000097:blood*; D006339:Heart Rate; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000097:blood*; D011187:Posture; D011863:Radioimmunoassay; D012083:Renin / Q000097:blood
D016232:Endothelins; D012083:Renin