Merck
  • Home
  • Search Results
  • Role of nitric oxide synthase isoforms for ophthalmic artery reactivity in mice.

Role of nitric oxide synthase isoforms for ophthalmic artery reactivity in mice.

Experimental eye research (2014-07-16)
Panagiotis Laspas, Evgeny Goloborodko, Jan J Sniatecki, Marcin L Kordasz, Caroline Manicam, Leszek Wojnowski, Huige Li, Andreas Patzak, Norbert Pfeiffer, Adrian Gericke
ABSTRACT

Nitric oxide synthases (NOS) are involved in regulation of ocular vascular tone and blood flow. While endothelial NOS (eNOS) has recently been shown to mediate endothelium-dependent vasodilation in mouse retinal arterioles, the contribution of individual NOS isoforms to vascular responses is unknown in the retrobulbar vasculature. Moreover, it is unknown whether the lack of a single NOS isoform affects neuron survival in the retina. Thus, the goal of the present study was to examine the hypothesis that the lack of individual nitric oxide synthase (NOS) isoforms affects the reactivity of mouse ophthalmic arteries and neuron density in the retinal ganglion cell (RGC) layer. Mice deficient in one of the three NOS isoforms (nNOS-/-, iNOS-/- and eNOS-/-) were compared to respective wild type controls. Intraocular pressure (IOP) was measured in conscious mice using rebound tonometry. To examine the role of each NOS isoform for mediating vascular responses, ophthalmic arteries were studied in vitro using video microscopy. Neuron density in the RGC layer was calculated from retinal wholemounts stained with cresyl blue. IOP was similar in all NOS-deficient genotypes and respective wild type controls. In ophthalmic arteries, phenylephrine, nitroprusside and acetylcholine evoked concentration-dependent responses that did not differ between individual NOS-deficient genotypes and their respective controls. In all genotypes except eNOS-/- mice, vasodilation to acetylcholine was markedly reduced after incubation with L-NAME, a non-isoform-selective inhibitor of NOS. In contrast, pharmacological inhibition of nNOS and iNOS had no effect on acetylcholine-induced vasodilation in any of the mouse genotypes. Neuron density in the RGC layer was similar in all NOS-deficient genotypes and respective controls. Our findings suggest that eNOS contributes to endothelium-dependent dilation of murine ophthalmic arteries. However, the chronic lack of eNOS is functionally compensated by NOS-independent vasodilator mechanisms. The lack of a single NOS isoform does not appear to affect IOP or neuron density in the RGC layer.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sodium bicarbonate, tested according to Ph. Eur.
Sigma-Aldrich
Acetylcholine iodide, ≥97%
Sigma-Aldrich
Magnesium sulfate solution, for molecular biology, 1.00 M±0.04 M
Sigma-Aldrich
Acetylcholine bromide, ≥99%
Sigma-Aldrich
Nω-Nitro-L-arginine methyl ester hydrochloride, ≥98% (TLC), powder
Sigma-Aldrich
Sodium bicarbonate, BioXtra, 99.5-100.5%
Sigma-Aldrich
Sodium bicarbonate, powder, BioReagent, for molecular biology, suitable for cell culture, suitable for insect cell culture
Supelco
Phenylephrine Hydrochloride, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Magnesium sulfate solution, BioUltra, for molecular biology
Phenylephrine hydrochloride, European Pharmacopoeia (EP) Reference Standard
USP
Sodium bicarbonate, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Sodium bicarbonate, Hybri-Max, powder, suitable for hybridoma, ≥99.5%
Sigma-Aldrich
Sodium bicarbonate, anhydrous, free-flowing, Redi-Dri, ReagentPlus®, ≥99.5%
Sigma-Aldrich
Sodium bicarbonate, anhydrous, free-flowing, Redi-Dri, ACS reagent, ≥99.7%
Sigma-Aldrich
Sodium bicarbonate, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99.7%
Sigma-Aldrich
Sodium nitroferricyanide(III) dihydrate, ACS reagent, ≥99%
Sigma-Aldrich
Sodium bicarbonate, puriss., meets analytical specification of Ph. Eur., BP, USP, FCC, E500, 99.0-100.5%, powder
Sigma-Aldrich
Sodium bicarbonate, ReagentPlus®, ≥99.5%, powder
Sigma-Aldrich
Sodium hydrogencarbonate, −40-+140 mesh, ≥95%
Sigma-Aldrich
Sodium bicarbonate, ACS reagent, ≥99.7%
Sigma-Aldrich
(R)-(−)-Phenylephrine hydrochloride, powder
Sigma-Aldrich
(R)-(−)-Phenylephrine hydrochloride, analytical standard
Sigma-Aldrich
Acetylcholine perchlorate
Sigma-Aldrich
Magnesium sulfate, BioReagent, suitable for cell culture, suitable for insect cell culture
Sigma-Aldrich
Sodium bicarbonate-12C, 99.9 atom % 12C
Sigma-Aldrich
Potassium phosphate monobasic, for molecular biology, ≥98.0%
Sigma-Aldrich
Potassium phosphate monobasic, powder, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99.0%
Sigma-Aldrich
Magnesium sulfate, ≥99.99% trace metals basis
Sigma-Aldrich
Potassium phosphate monobasic, 99.99% trace metals basis
Sigma-Aldrich
Potassium phosphate monobasic, tested according to Ph. Eur., anhydrous