Endothelin–1 Plasma Levels in Retinitis Pigmentosa Patients

Abstract

Abstract: : Purpose: to evaluate the relation between endothelin–1 plasma levels and Retinitis Pigmentosa (RP). Methods:We performed blood samples in 40 patients affected by RP followed in our department of inhered diseases of University of Rome "La Sapienza". This group was compared with a control group of 40 people age and sex matched. We performed a complete ophthalmologic examination including: BCVA, indirect ophthalmoscopy evaluating degree of RPE atrophy and severity of pigmentation, visual field, ERG. The study group included 26 patients with RP and 14 patients with syndromic RP (8 patients affected by Usher’s syndrome (US), 5 patients with a Cone–Rod dystrophy and 1 with Laurence–Moon–Bardet–Biedl Syndrome (LMBBS). Patients were sampled from cubital vein of 20cc of blood in EDTA vacutainer. The determination of the endothelin–1 plasmatic concentration, after extraction and purification on Sep–Pak–18 cartrige, was made with radiological method (Phoenix Lab, Mountain View, CA, USA). Results:in the average population ET–1 plasma levels ranges between 6.30pg/ml and 9.50pg/ml while in our group Endothelin–1 concentration were significantly increased, patients showed 16.2±5.6 pg/ml and difference evaluated between two groups with Student’s "t" test were highly statistically significant (p<0.0001). Our patients were divided in Syndromic RP with a mean of 18.9±6.8 and RP patients with a mean of 14.7±4.2. DISCUSSION: Literature data clearly showed a reduction in the retinal and choroidal blood flood (Grunwald et all and Langham et all.) in patients with RP. ET–1 is considered one of the most potent vasoconstrictor of small and large vessels (Masaki et all). On the basis of our results, ET–1 might play have an important pathogenetic role in the RP retinal damage due to local vasoconstriction. Hyperoxygenation was demonstrated to be useful in the treatment of young RP patients (Vingolo et all) nonetheless it is one of the major stimulation factor of ET–1. In future, reducing ET–1 levels might be useful to increase hyperbaric therapy benefits.

Keywords: retinitis • retinal degenerations: hereditary • growth factors/growth factor receptors