Mitochondrial Physiology Network 10.9: 13-14 (2005) - download pdf

Mitochondrial regular arrangement in muscle cells: a “crystal-like" pattern.

Nathalie Béraud¹, M Vendelin^1,2, K Guerrero¹, VA Saks^1,3

¹Group of Quantitative and Structural Bioenergetics, Laboratory of Fundamental and Applied Bioenergetics, INSERM E0221, Joseph Fourier University, Grenoble, France; ²Institute of Cybernetics, Tallinn Technical University, Akadeemia 21, 12618 Tallinn, Estonia;  ³Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Akadeemia 21, Tallinn, Estonia. - nathalie.beraud@ujf-grenoble.fr

    The aim of this work is to characterize quantitatively the arrangement of mitochondria in heart and skeletal muscles. For this, we studied confocal images of mitochondria in non-fixed cardiomyocytes and fibers from soleus and white gastrocnemius muscles of adult rats. The arrangement of intermyofibrillar mitochondria was analyzed by estimating the densities of distribution of mitochondrial centers relative to each other (the probability density function).

    In cardiomyocytes (1820 mitochondrial centers marked), neighboring mitochondria are aligned along rectangle, with distance between the centers equal to 1.97 ± 0.43 mm and 1.43 ± 0.43 mm in longitudinal and transversal directions, respectively.

    In soleus (1659 mitochondrial centers marked) and in white gastrocnemius (621 pairs of mitochondria marked), mitochondria are mainly organized in pairs at the level of I-band. Due to such organization, there are two distances characterizing mitochondrial distribution in longitudinal direction in these muscles. The distance between mitochondrial centers in longitudinal direction within the same I-band is 0.91 ± 0.11 mm and 0.61 ± 0.07 mm in soleus and white gastrocnemius, respectively. The distance between mitochondrial centers in different I-bands is est » 3.7 mm and » 3.3 mm in soleus and in gastrocnemius, respectively. In the transversal direction, the mitochondria are packed considerably closer to each other in soleus than in white gastrocnemius | the distance is equal 0.75 ± 0.22 mm (soleus) and 1.09 ± 0.41 mm (gastrocnemius).

    Our results show that intermyofibrillar mitochondria are arranged in highly ordered crystal-like pattern in a muscle-specific manner with relatively small deviation in the distances between neighboring mitochondria. This is consistent with the concept of the unitary nature of the organization of the muscle energy metabolism ^b.

1.  Vendelin M, Béraud N, Guerrero K, Andrienko T, Kuznetsov A, Olivares J, Kay L, Saks V (2005) Mitochondrial regular arrangement in muscle cells : a “cristal-like” pattern. Am. J. Physiol. Cell. Physiol. 288: C735-C767.

2.  Saks V, Kaambre T, Sikk P, Eimre M, Orlova E, Paju K, Piirsoo A, Appaix F, Kay L, Regitz-Zagrosek V, Fleck E, Seppet E (2001) Intracellular energetic units in red muscle cells. Mol. Cell. Biochem. 356: 643-657.