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Advanced age protects microvascular endothelium from aberrant Ca 2+ influx and cell death induced by hydrogen peroxide
Author(s) -
Socha Matthew J.,
Boerman Erika M.,
Behringer Erik J.,
Shaw Rebecca L.,
Domeier Timothy L.,
Segal Steven S.
Publication year - 2015
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jp270169
Subject(s) - endothelium , oxidative stress , calcium , endocrinology , calcium in biology , endothelial stem cell , endothelial dysfunction , medicine , intracellular , chemistry , biochemistry , in vitro
Key points Calcium signalling in endothelial cells of resistance arteries is integral to blood flow regulation. Oxidative stress and endothelial dysfunction can prevail during advanced age and we questioned how calcium signalling may be affected. Intact endothelium was freshly isolated from superior epigastric arteries of Young (∼4 months) and Old (∼24 months) male C57BL/6 mice. Under resting conditions, with no difference in intracellular calcium levels, hydrogen peroxide (H 2 O 2 ) availability was ∼1/3 greater in endothelium of Old mice while vascular catalase activity was reduced by nearly half. Compared to Old, imposing oxidative stress (200 μ m H 2 O 2 ) for 20 min increased intracellular calcium to 4‐fold greater levels in endothelium of Young in conjunction with twice the calcium influx. Prolonged (60 min) exposure to H 2 O 2 induced 7‐fold greater cell death in endothelium of Young. Microvascular adaptation to advanced age may protect endothelial cells during elevated oxidative stress to preserve functional viability of the intima.Abstract Endothelial cell Ca 2+ signalling is integral to blood flow control in the resistance vasculature yet little is known of how its regulation may be affected by advancing age. We tested the hypothesis that advanced age protects microvascular endothelium by attenuating aberrant Ca 2+ signalling during oxidative stress. Intact endothelial tubes (width, ∼60 μm; length, ∼1000 μm) were isolated from superior epigastric arteries of Young (3–4 months) and Old (24–26 months) male C57BL/6 mice and loaded with Fura‐2 dye to monitor [Ca 2+ ] i . At rest there was no difference in [Ca 2+ ] i between age groups. Compared to Young, the [Ca 2+ ] i response to maximal stimulation with acetylcholine (3 μ m , 2 min) was ∼25% greater in Old, confirming signalling integrity with advanced age. Basal H 2 O 2 availability was ∼33% greater in Old while vascular catalase activity was reduced by half. Transient exposure to elevated H 2 O 2 (200 μ m , 20 min) progressively increased [Ca 2+ ] i to ∼4‐fold greater levels in endothelium of Young versus Old. With no difference between age groups at rest, Mn 2+ quench of Fura‐2 fluorescence revealed 2‐fold greater Ca 2+ influx in Young during elevated H 2 O 2 ; this effect was attenuated by ∼75% using ruthenium red (5 μ m ) as a broad‐spectrum inhibitor of transient receptor potential channels. Prolonged exposure to H 2 O 2 (200 μ m , 60 min) induced ∼7‐fold greater cell death in endothelium of Young versus Old. Thus, microvascular endothelium can adapt to advanced age by reducing Ca 2+ influx during elevated oxidative stress. Protection from cell death during oxidative stress will sustain endothelial integrity during ageing.