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Functional NOS 1 in the rat mesenteric arterial bed.
Jennifer C Sullivan1, Ararat D Giulumian, David M Pollock
1Vascular Biology Center, Medical College of Georgia, 1459 Laney-Walker Boulevard, Augusta, GA 30912, USA. jsullivan@mail.mcg.edu
Summary
Functional nitric oxide synthase (NOS) 1 exists in resistance arteries, impacting blood pressure regulation. This study confirms NOS 1 activity and expression in these critical vessels.
Area of Science:
- Physiology
- Vascular Biology
- Biochemistry
Background:
- Large arteries possess functional nitric oxide synthase (NOS) 1.
- Resistance arteries are key determinants of blood pressure.
Purpose of the Study:
- To investigate the presence and function of NOS 1 in rat mesenteric resistance arteries.
- To determine the isoforms and localization of NOS 1 in these vessels.
Main Methods:
- Measurement of phenylephrine (PE) contraction in isolated arteries with and without the NOS 1 inhibitor N(5)-(1-imino-3-butenyl)-L-ornithine (VNIO).
- Assay of NOS activity in arterial bed fractions using [(3)H]arginine to [(3)H]citrulline conversion.
- Immunoprecipitation and Western blot analysis to identify NOS 1 isoforms and their distribution.
Main Results:
- VNIO significantly increased PE sensitivity in both endothelium-intact and -denuded resistance arteries.
- Approximately 40% of NOS activity in arterial bed fractions was inhibited by VNIO.
- Western blot revealed two NOS 1 isoforms, with distinct localization in cytosolic and particulate fractions.
Conclusions:
- Functional NOS 1 is present in rat mesenteric resistance arteries.
- NOS 1 contributes to the regulation of vascular tone in these arteries.
- Evidence supports the existence of at least two NOS 1 isoforms in resistance arteries.