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Arterioscler Thromb Vasc Biol. 2016 Jan;36(1):97-107. doi: 10.1161/ATVBAHA.115.306499. Epub 2015 Nov 5.

Disruption of Physiological Balance Between Nitric Oxide and Endothelium-Dependent Hyperpolarization Impairs Cardiovascular Homeostasis in Mice.

Author information

1
From the Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
2
From the Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan. shimo@cardio.med.tohoku.ac.jp.

Abstract

OBJECTIVE:

Endothelium-derived nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) play important roles in modulating vascular tone in a distinct vessel size-dependent manner; NO plays a dominant role in conduit arteries and EDH in resistance vessels. We have recently demonstrated that endothelial NO synthase (eNOS) is functionally suppressed in resistance vessels through caveolin-1 (Cav-1)-dependent mechanism, switching its function from NO to EDH/hydrogen peroxide generation in mice. Here, we examined the possible importance of the physiological balance between NO and EDH in cardiovascular homeostasis.

APPROACH AND RESULTS:

We used 2 genotypes of mice in which eNOS activity is genetically upregulated; Cav-1-knockout (Cav-1-KO) and endothelium-specific eNOS transgenic (eNOS-Tg) mice. Isometric tension recordings and Langendorff experiments with isolated perfused hearts showed that NO-mediated relaxations were significantly enhanced, whereas EDH-mediated relaxations were markedly reduced in microcirculations. Importantly, impaired EDH-mediated relaxations of small mesenteric arteries from Cav-1-KO mice were completely rescued by crossing the mice with those with endothelium-specific overexpression of Cav-1. Furthermore, both genotypes showed altered cardiovascular phenotypes, including cardiac hypertrophy in Cav-1-KO mice and hypotension in eNOS-Tg mice. Finally, we examined cardiac responses to chronic pressure overload by transverse aortic constriction in vivo. When compared with wild-type mice, both Cav-1-KO and eNOS-Tg mice exhibited reduced survival after transverse aortic constriction associated with accelerated left ventricular systolic dysfunction, reduced coronary flow reserve, and enhanced myocardial hypoxia.

CONCLUSIONS:

These results indicate that excessive endothelium-derived NO with reduced EDH impairs cardiovascular homeostasis in mice in vivo.

KEYWORDS:

caveolin-1; endothelium; endothelium-dependent hyperpolarization factor; nitric oxide

PMID:
26543099
DOI:
10.1161/ATVBAHA.115.306499
[Indexed for MEDLINE]

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