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Age decreases mitochondrial motility and increases mitochondrial size in vascular smooth muscle

Chalmers, S.; Saunter, C.D.; Girkin, J.M.; McCarron, J.G.

Age decreases mitochondrial motility and increases mitochondrial size in vascular smooth muscle Thumbnail


Authors

S. Chalmers

C.D. Saunter

J.G. McCarron



Abstract

Mitochondrial function, motility and architecture are each central to cell function. Age-associated mitochondrial dysfunction may contribute to vascular disease. However, mitochondrial changes in ageing remain ill-defined because of the challenges of imaging in native cells. We determined the structure of mitochondria in live native cells, demarcating boundaries of individual organelles by inducing stochastic ‘flickers’ of membrane potential, recorded as fluctuations in potentiometric fluorophore intensity (flicker-assisted localization microscopy; FaLM). In freshly-isolated myocytes from rat cerebral resistance arteries, FaLM showed a range of mitochondrial X-Y areas in both young adult (3 months; 0.05–6.58 μm2) and aged rats (18 months; 0.05–13.4 μm2). In cells from young animals, most mitochondria were small (mode area 0.051 μm2) compared to aged animals (0.710 μm2). Cells from older animals contained a subpopulation of highly-elongated mitochondria (5.3% were >2 μm long, 4.2% had a length:width ratio >3) that was rare in younger animals (0.15% of mitochondria >2 μm long, 0.4% had length:width ratio >3). The extent of mitochondrial motility also varied. 1/811 mitochondria observed moved slightly (∼0.5 μm) in myocytes from older animals, whereas, in the younger animals, directed and Brownian-like motility occurred regularly (215 of 1135 mitochondria moved within 10 min, up to distance of 12 μm). Mitochondria positioned closer to the cell periphery showed a greater tendency to move. In conclusion, cerebral vascular myocytes from young rats contained small, motile mitochondria. In aged rats, mitochondria were larger, immobile and could be highly-elongated. These age-associated alterations in mitochondrial behaviour may contribute to alterations in cell signalling, energy supply or the onset of proliferation.

Citation

Chalmers, S., Saunter, C., Girkin, J., & McCarron, J. (2016). Age decreases mitochondrial motility and increases mitochondrial size in vascular smooth muscle. The Journal of Physiology, 594(15), 4283-4295. https://doi.org/10.1113/jp271942

Journal Article Type Article
Acceptance Date Feb 26, 2016
Online Publication Date Apr 9, 2016
Publication Date Aug 1, 2016
Deposit Date Apr 11, 2016
Publicly Available Date Mar 28, 2024
Journal Journal of Physiology
Print ISSN 0022-3751
Electronic ISSN 1469-7793
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 594
Issue 15
Pages 4283-4295
DOI https://doi.org/10.1113/jp271942

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Copyright Statement
© 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.







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