skip to main content


Search for: All records

Creators/Authors contains: "Norton, Charles E."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Key points

    Vascular oxidative stress increases with advancing age.

    We hypothesized that resistance vessels develop resilience to oxidative stress to protect functional integrity and tested this hypothesis by exposing isolated pressurized superior epigastric arteries (SEAs) of old and young mice to H2O2.

    H2O2‐induced death was greater in smooth muscle cells (SMCs) than endothelial cells (ECs) and lower in SEAs from oldvs. young mice; the rise in vessel wall [Ca2+]iinduced by H2O2was attenuated with ageing, as was the decline in noradrenergic vasoconstriction; genetic deletion of IL‐10 mimicked the effects of advanced age on cell survival.

    Inhibiting NO synthase or scavenging peroxynitrite reduced SMC death; endothelial denudation or inhibiting gap junctions increased SMC death; delocalization of cytochrome C activated caspases 9 and 3 to induce apoptosis.

    Vascular cells develop resilience to H2O2during ageing by preventing Ca2+overload and endothelial integrity promotes SMC survival.

    Abstract

    Advanced age is associated with elevated oxidative stress and can protect the endothelium from cell death induced by H2O2. Whether such protection occurs for intact vessels or differs between smooth muscle cell (SMC) and endothelial cell (EC) layers is unknown. We tested the hypothesis that ageing protects SMCs and ECs during acute exposure to H2O2(200 µm, 50 min). Mouse superior epigastric arteries (SEAs; diameter, ∼150 µm) were isolated and pressurized to 100 cmH2O at 37˚C. For SEAs from young (4 months) mice, H2O2killed 57% of SMCs and 11% of ECs in malesvs. 8% and 2%, respectively, in females. Therefore, SEAs from males were studied to resolve the effect of ageing and experimental interventions. For old (24 months) mice, SMC death was reduced to 10% with diminished accumulation of [Ca2+]iin the vessel wall during H2O2exposure. In young mice, genetic deletion of IL‐10 mimicked the protective effect of ageing on cell death and [Ca2+]iaccumulation. Whereas endothelial denudation or gap junction inhibition (carbenoxolone; 100 µm) increased SMC death, inhibiting NO synthase (l‐NAME, 100 µm) or scavenging peroxynitrite (FeTPPS, 5 µm) reduced SMC death along with [Ca2+]i. Despite NO toxicity via peroxynitrite formation, endothelial integrity protects SMCs. Caspase inhibition (Z‐VAD‐FMK, 50 µm) attenuated cell death with immunostaining for annexin V, cytochrome C, and caspases 3 and 9 pointing to induction of intrinsic apoptosis during H2O2exposure. We conclude that advanced age reduces Ca2+influx that triggers apoptosis, thereby promoting resilience of the vascular wall during oxidative stress.

     
    more » « less