Erythrocyte nitric oxide in glaucoma patients - ex vivo study.
BACKGROUND
Glaucoma is an optic neuropathy associated with vascular dysregulation and increased intra-ocular pressure (IOP). Timolol is used as treatment for reducing IOP, by limiting aqueous humour production. Increased NOS expression as well as decreased levels of nitric oxide (NO) metabolites, and high activity of erythrocyte acetylcholinesterase (AChE) were observed in primary open angle glaucoma patients.


OBJECTIVE
This ex vivo study aims to evaluate timolol effect in NO efflux and its derivatives in glaucoma patient's erythrocytes.


METHODS
Venous blood from 15 glaucoma patients was collected. Erythrocyte suspensions were incubated with the AChE modulators acetylcholine (ACh) and timolol at 10 μM. Erythrocyte NO efflux and S-nitrosoglutathione (GSNO) concentration were measured.


RESULTS
No significant differences were obtained in erythrocyte NO efflux and GSNO concentration in response to ACh or timolol when compared with the untreated erythrocytes of glaucoma patients. When comparing the same incubation conditions for erythrocyte suspensions between glaucoma patients and healthy subjects, those from glaucoma patients showed higher NO efflux in presence and absence of timolol, and higher values of GSNO in the presence of timolol.


CONCLUSIONS
We demonstrated that erythrocytes from glaucoma patients have similar availability to release NO both in absence and presence of timolol, and have higher GSNO values in presence of timolol.
Carlota Saldanha Lab, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa. Lisboa, Portugal.
Rita
R
Esteves
Carlota Saldanha Lab, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa. Lisboa, Portugal.
Teresa
T
Freitas
Carlota Saldanha Lab, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa. Lisboa, Portugal.
Pedro
P
Teixeira
Carlota Saldanha Lab, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa. Lisboa, Portugal.
Patrícia
P
Napoleão
Faculdade de Medicina, Universidade de Lisboa, ISAMB, CECU Coordenator, ALM Clinical Director.
Carlos
C
Neves
Carlota Saldanha Lab, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa. Lisboa, Portugal.
Carlota
C
Saldanha
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005901:Glaucoma / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood*; D013999:Timolol / Q000008:administration & dosage / Q000627:therapeutic use*
D000319:Adrenergic beta-Antagonists; D009569:Nitric Oxide; D013999:Timolol
ACh; GSNO; Glaucoma; erythocyte; nitric oxide; timolol