title: Glaucoma patients present increased levels of diadenosine tetraphosphate, Ap(4)A, in the aqueous humour.
abstract: Previous studies have shown the presence of diadenosine tetraphosphate (Ap(4)A) and pentaphosphate (Ap(5)A) in the aqueous humour (AH) of different species. When topically applied to the rabbit cornea, Ap(4)A decreased IOP while Ap(5)A increased it. Here we study the presence of dinucleoside polyphosphates in the AH from human patients with or without glaucoma. AH was obtained at the time of cataract surgery from patients with (n=16) or without (n=10) primary open-angle glaucoma. AH (0.1-0.2 ml) was collected at the beginning of surgery through a corneal paracentesis and immediately cooled in liquid nitrogen, kept frozen and protected from light. AH aliquots were analyzed by HPLC for the presence of Ap(4)A and Ap(5)A. Both, Ap(4)A and Ap(5)A were detected in the AH of both experimental groups. No significant differences were found for Ap(5)A. In contrast, Ap(4)A levels were increased by ∼15-fold in the AH from glaucomatous eyes ranging from 19.5±9.2 nM in normal individuals to 286.03±30.9 nM in glaucomatous patients. In conclusion, both Ap(4)A and Ap(5)A were detected for the first time in human AH. Interestingly, glaucomatous eyes presented elevated concentrations of Ap(4)A compared to controls. The role of Ap(4)A needs to be elucidated but it may help to protect the autonomic innervation in the ciliary body/trabecular meshwork. Also, because of its higher levels in glaucoma patients it may be considered as a possible glaucoma biomarker.
authors.affiliation: Hospital Sagrat Cor-ICR, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Castany
authors.forename: Isabel
authors.initials: I
authors.lastname: Jordi
authors.forename: Jaume
authors.initials: J
authors.lastname: Catala
authors.forename: Arcadi
authors.initials: A
authors.lastname: Gual
authors.forename: Miguel
authors.initials: M
authors.lastname: Morales
authors.forename: Xavier
authors.initials: X
authors.lastname: Gasull
authors.forename: Jesus
authors.initials: J
authors.lastname: Pintor
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001082:Aqueous Humor / Q000378:metabolism*; D002387:Cataract Extraction; D002851:Chromatography, High Pressure Liquid; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000378:metabolism*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution
chemical_list: D015226:Dinucleoside Phosphates; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C020733:diadenosine tetraphosphate