Ascorbate attenuates red light mediated vasodilation: Potential role of S-nitrosothiols

Figures

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  Fig. 1. Ascorbate effect on red light-dependent vasodilation. (A): Dilation of isolated facial arteries of C57BI/6 mice (pressurized to 60 mmHg before pre-constriction with U46619) with and without pre-incubation of sodium ascorbate (15 mM for 60 min) upon irradiation (670 nm, 6 J/cm2). Values are means±SE, N = 8, *p < 0.05. (B): Representative trace of triiodide-based chemiluminescence analysis of artery tissue homogenized in phosphate/DTPA/NEM pH 7.4. Arrows indicate injection of samples from control and ascorbate treated vessel, protein content: 19 and 25 µg, respectively. (C): Quantification chemiluminescence data. N = 4, *p < 0.05.

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  Fig. 2. Ascorbate effect on acetylcholine-induced vasodilation. Dilation of isolated facial arteries of C57BI/6 mice (pressurized to 60 mmHg before pre-constriction with U46619) as a function of acetylcholine concentration with and without pre-incubation of sodium ascorbate (15 mM for 60 min). Values are means ± SE, N = 6.

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  Fig. 3. Adoptive transfer. Facial arteries from C57Bl/6 mice were isolated and pressurized to 60 mmHg before pre-constriction with U46619 (n = 8). A) After 10 min of light exposure, the bath solution from vessel 1 was added to vessel 2. B) Preincubation with 15 mM ascorbate reduces dilation in both the treated vessel 1 (17.1%, SD 3.2, SE 1.2) as well as the bath transfer vessel 2 (23.4%, SD 6.6, SE 2.5).

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  Fig. 4. GSNO-dependent vasodilation. Facial arteries from C57Bl/6 mice were isolated and pressurized to 60 mmHg before pre-constriction with U46619 (n = 8). A) Pre-constricted vessel was exposed to 40 nM GSNO (diamonds), or 40 nM GSNO pre-incubated with 15 mM ascorbate (squares). B) Pre-constricted vessel was exposed to increasing concentrations of GSNO. The maximal dilations after 10 min were plotted as a function of GSNO concentration. Arrows indicate GSNO concentrations at the maximal dilations on (A) panel without (dashed line) and with (dotted line) ascorbate treatment. Values are means ± SE, N = 4, *p < 0.05.

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  Fig. 5. DNIC-dependent vasodilation. Facial arteries from C57Bl/6 mice were isolated and pressurized to 60 mmHg before pre-constriction with U46619 (n = 8). A) Pre-constricted vessel was exposed to 40 nM GSH-DNIC (diamonds), or 40 nM GSH-DNIC pre-incubated with 15 mM ascorbate (squares). Values are means ± SE, N = 4, *p < 0.05 B) DNIC-GSH (70 µM) was incubated with sodium ascorbate (15 mM), or with dehydoascorbate (DHA, 1.5 mM and 15 mM) at 37 °C in 50 mM Hepes, pH 7.4. DNIC levels were determined at 0, and 60 min after separation with HPLC/detection at 312 nm. Values are means ± SE, N = 3.

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  Fig. 6. Mechanism of light-mediated NO-dependent vasorelaxation.