title: Mitochondrial subpopulations and heterogeneity revealed by confocal imaging: possible physiological role?
abstract: Heterogeneity of mitochondria has been reported for a number of various cell types. Distinct mitochondrial subpopulations may be present in the cell and may be differently involved in physiological and pathological processes. However, the origin and physiological roles of mitochondrial heterogeneity are still unknown. In mice skeletal muscle, a much higher oxidized state of subsarcolemmal mitochondria as compared with intermyofibrillar mitochondria has been demonstrated. Using confocal imaging technique, we present similar phenomenon for rat soleus and gastrocnemius muscles, where higher oxidative state of mitochondrial flavoproteins correlates also with elevated mitochondrial calcium. Moreover, subsarcolemmal mitochondria demonstrate distinct arrangement and organization. In HL-1 cardiomyocytes, long thread mitochondria and small grain mitochondria are observed irrespective of a particular cellular region, showing also heterogeneous membrane potential and ROS production. Possible physiological roles of intracellular mitochondrial heterogeneity and specializations are discussed.
authors.affiliation: Daniel Swarovski Research Laboratory, Innsbruck Medical University, Innrain 66, A-6020 Innsbruck, Austria. andrei.kuznetsov@uibk.ac.at
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Kuznetsov
authors.forename: Jakob
authors.initials: J
authors.lastname: Troppmair
authors.forename: Robert
authors.initials: R
authors.lastname: Sucher
authors.forename: Martin
authors.initials: M
authors.lastname: Hermann
authors.forename: Valdur
authors.initials: V
authors.lastname: Saks
authors.forename: Raimund
authors.initials: R
authors.lastname: Margreiter
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D005420:Flavoproteins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry; D066298:In Vitro Techniques; D008564:Membrane Potentials; D018613:Microscopy, Confocal; D008929:Mitochondria, Heart / Q000378:metabolism* / Q000648:ultrastructure; D008931:Mitochondria, Muscle / Q000378:metabolism* / Q000648:ultrastructure; D018485:Muscle Fibers, Skeletal / Q000502:physiology* / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000648:ultrastructure; D010084:Oxidation-Reduction; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D012508:Sarcolemma / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D005420:Flavoproteins; D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species; D002118:Calcium