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Single organelle localisation microscopy in vascular smooth muscle reveals mitochondrial networks are multiple electrically‐discontinuous elements, with larger organelle dimensions and more extensive mitochondrial clustering occurring in hypertension (757.2)
Author(s) -
Chalmers Susan,
Saunter Christopher,
Girkin John,
McCarron John
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.757.2
Subject(s) - organelle , mitochondrion , microbiology and biotechnology , membrane potential , biology , actin , vascular smooth muscle , biophysics , fluorescence microscope , chemistry , smooth muscle , fluorescence , endocrinology , physics , quantum mechanics
Mitochondria vary from being small puncta to large interconnected networks. While more easily visualized in cultured cells, the precise structure of the organelle in native cells is poorly understood due to the cells’ complex organization and to imaging resolution limitations. In native cells, mitochondrion dimensions vary from ~0.5μm to ~7μm diameter. Here, the electrical changes arising from transient de‐ and re‐polarisations of membrane potential (‘flickers’) of single mitochondria within native vascular smooth muscle cells were visualised by fluorescence imaging and used to determine the organelles’ dimensions, position and relationship with Ca 2+ signals. Cross‐correlation of changes in fluorescence intensity over a 40x40 pixel area around each image pixel was used to produce high‐resolution images of mitochondrial boundaries. This functionally resolved single organelle localisation microscopy (SOLM) reveals multiple electrically‐discontinuous mitochondrial elements within what appeared to be a single large organelle, i.e. a dense mitochondrial cluster. Significantly, both the size of individual mitochondria and extent of organelle clustering increased in resistance artery myocytes from spontaneously hypertensive (SHR) rats when compared to normotensive (WKY) controls. The Ca 2+ signal evoked by plasma membrane depolarization was largest near mitochondrial clusters. In vascular smooth muscle, the extent of mitochondrial networking and organelle mobility correlates with cellular proliferation and disease. Here a previously unrecognised change in mitochondrial structure may contribute to changes in Ca 2+ signalling and smooth muscle function characteristic of hypertension. Grant Funding Source : Supported by the Wellcome Trust (092292/Z/10/Z) and British Heart Foundation (PG/11/70/29086)