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Chronic deficit in nitric oxide elicits oxidative stress and augments T-type calcium-channel contribution to vascular tone of rodent arteries and arterioles.

Abstract：

AIMS:As cardiovascular disease is characterized by reduced nitric oxide bioavailability, our aim was to determine the impact of this change on the mechanism underlying vascular tone of pressurized arteries in vitro and in vivo. METHODS AND RESULTS:We used pressurized cerebral and mesenteric arteries in vitro and skeletal muscle arterioles in vivo to study the contribution of L-type (1 µmol/L nifedipine) and T-type (1 µmol/L mibefradil, 3 µmol/L NNC 55-0396) calcium channels to vascular tone, following acute or chronic inhibition of nitric oxide. Acute inhibition with l-NAME (10 µmol/L) significantly increased the T-type, but not the L-type, channel contribution to vascular tone in vitro and in vivo, and altered the smooth muscle expression of the Cav3.1 and Cav3.2 T-type channels. In pressurized mesenteric arteries of Cav3.1ko and Cav3.2ko mice, acutely treated with l-NAME, the contribution of T-type channels relative to L-type channels was significantly reduced, compared with arteries from wild-type mice.Chronic l-NAME treatment (40 mg/kg/day; 14-18 days) increased blood pressure, vascular superoxide, and the contribution of T-type channels to vascular tone in vivo. The latter was reversed by acute scavenging of superoxide with tempol (1 mmol/L), or inhibition of NADPH oxidase with apocynin (500 µmol/L) or DPI (5 µmol/L). CONCLUSION:We conclude that nitric oxide deficit produces a significant increase in the contribution of Cav3.1 and Cav3.2 T-type calcium channels to vascular tone, by regulating the bioavailability of reactive oxygen species produced by NADPH oxidase. Our data provide evidence for a novel causal link between nitric oxide deficit, oxidative stress, and T-type calcium channel function.

journal_name

Cardiovasc Res

journal_title

Cardiovascular research

authors

Howitt L,Kuo IY,Ellis A,Chaston DJ,Shin HS,Hansen PB,Hill CE

doi

10.1093/cvr/cvt043

subject

Has Abstract

pub_date

2013-06-01 00:00:00

pages

449-57

issue

eissn

0008-6363

issn

1755-3245

pii

cvt043

journal_volume

pub_type

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Chronic deficit in nitric oxide elicits oxidative stress and augments T-type calcium-channel contribution to vascular tone of rodent arteries and arterioles.