Aging Exacerbates Pressure-Induced Mitochondrial Oxidative Stress in Mouse Cerebral Arteries

Epidemiological studies demonstrate that in addition to the increased prevalence of hypertension in old patients, the deleterious cerebrovascular effects of hypertension (including atherosclerosis, stroke, and vascular cognitive impairment) are also exacerbated in elderly individuals. The cellular mechanisms by which aging and hypertension interact to promote cerebrovascular pathologies are not well understood. To test the hypothesis that aging exacerbates high pressure-induced mitochondrial oxidative stress, we exposed isolated segments of the middle cerebral arteries of young (3 months) and aged (24 months) C57BL/6 mice to 60 or 140 mmHg intraluminal pressure and assessed changes in mitochondrial reactive oxygen species production using a mitochondria-targeted redox-sensitive fluorescent indicator dye (MitoSox) by confocal microscopy. Perinuclear MitoSox fluorescence was significantly stronger in high pressure-exposed middle cerebral arteries compared with middle cerebral arteries of the same animals exposed to 60 mmHg, indicating that high pressure increases mitochondrial reactive oxygen species production in the smooth muscle cells of cerebral arteries. Comparison of young and aged middle cerebral arteries showed that aging exacerbates high pressure-induced mitochondrial reactive oxygen species production in cerebral arteries. We propose that increased mechanosensitive mitochondrial oxidative stress may potentially exacerbate cerebrovascular injury and vascular inflammation in aging.