TY - JOUR
T1 - Real-time direct measurement of nitric oxide in bovine perfused eye trabecular meshwork using a Clark-type electrode
AU - Millar, John Cameron
PY - 2003/1/1
Y1 - 2003/1/1
N2 - NO was detected in bovine trabecular meshwork (TM). Bovine eyes were perfused (posterior ciliary artery). In some eyes (operated eyes) a NO electrode was inserted adjacent to the TM (scleral flap). Vascular perfusion/intraocular pressures (VPP/IOP) were recorded. In operated eyes, epinephrine (1 nM-100 μM) increased NO (maximally 979.9 ± 117.6 nM, mean ± SDM). Timolol (1 mM) shifted the epinephrine-NO concentration-response curve rightward (2.94 log units) without significantly changing the maximal response (903.0 ± 67.7 nM, mean ± SDM). The non-selective NO synthase (NOS) inhibitor L-NMMA (100 μM) virtually abolished the NO response to epinephrine. L-NMMA alone (1 μM-100 μM) significantly reduced tonic NO generation (maximally 109.5 ± 24.9 nM, mean ± SDM), whereas timolol alone (1 μM-1 mM) had no effect. In unoperated eyes, epinephrine (1 nM-100 μM) reduced IOP (maximally 2.56 ± 0.64 mmHg, mean ± SDM). Epinephrine (100 μM) mildly increased VPP (4.6 ± 1.3 mmHg, mean ± SDM). Baseline aqueous humor formation rate (11.5 ± 3.2 μl/min, mean ± SDM) was unaffected. Effluent perfusate (effusate) total NO2- was determined by enzymatically reducing all NO3- to NO 2-, then assessing resultant NO2- (Griess assay). Epinephrine (1 nM-100 μM) increased effusate NO 2- (maximally 15.8 ± 4.9 μM, mean ± SDM). Timolol (1 mM) reduced, and L-NMMA (100 μM) virtually abolished effusate NO2- response to epinephrine. L-NMMA alone (1 μM-100 μM) reduced tonic effusate NO2- (maximally from 5.8 ± 1.6 μM to 1.1 ± 0.9 μM, mean ± SDM), whereas timolol alone (1 μM-1 mM) had no effect. NO is generated tonically in bovine TM and increases in response to epinephrine.
AB - NO was detected in bovine trabecular meshwork (TM). Bovine eyes were perfused (posterior ciliary artery). In some eyes (operated eyes) a NO electrode was inserted adjacent to the TM (scleral flap). Vascular perfusion/intraocular pressures (VPP/IOP) were recorded. In operated eyes, epinephrine (1 nM-100 μM) increased NO (maximally 979.9 ± 117.6 nM, mean ± SDM). Timolol (1 mM) shifted the epinephrine-NO concentration-response curve rightward (2.94 log units) without significantly changing the maximal response (903.0 ± 67.7 nM, mean ± SDM). The non-selective NO synthase (NOS) inhibitor L-NMMA (100 μM) virtually abolished the NO response to epinephrine. L-NMMA alone (1 μM-100 μM) significantly reduced tonic NO generation (maximally 109.5 ± 24.9 nM, mean ± SDM), whereas timolol alone (1 μM-1 mM) had no effect. In unoperated eyes, epinephrine (1 nM-100 μM) reduced IOP (maximally 2.56 ± 0.64 mmHg, mean ± SDM). Epinephrine (100 μM) mildly increased VPP (4.6 ± 1.3 mmHg, mean ± SDM). Baseline aqueous humor formation rate (11.5 ± 3.2 μl/min, mean ± SDM) was unaffected. Effluent perfusate (effusate) total NO2- was determined by enzymatically reducing all NO3- to NO 2-, then assessing resultant NO2- (Griess assay). Epinephrine (1 nM-100 μM) increased effusate NO 2- (maximally 15.8 ± 4.9 μM, mean ± SDM). Timolol (1 mM) reduced, and L-NMMA (100 μM) virtually abolished effusate NO2- response to epinephrine. L-NMMA alone (1 μM-100 μM) reduced tonic effusate NO2- (maximally from 5.8 ± 1.6 μM to 1.1 ± 0.9 μM, mean ± SDM), whereas timolol alone (1 μM-1 mM) had no effect. NO is generated tonically in bovine TM and increases in response to epinephrine.
UR - http://www.scopus.com/inward/record.url?scp=0042972860&partnerID=8YFLogxK
U2 - 10.1089/108076803322279363
DO - 10.1089/108076803322279363
M3 - Article
C2 - 12964955
AN - SCOPUS:0042972860
SN - 1080-7683
VL - 19
SP - 299
EP - 313
JO - Journal of Ocular Pharmacology and Therapeutics
JF - Journal of Ocular Pharmacology and Therapeutics
IS - 4
ER -