Branovets J, Sepp M, Kotlyarova S, Jepihhina N, Sokolova N, Aksentijevic D, Lygate CA, Neubauer S, Vendelin M, Birkedal R Am. J. Physiol. Heart Circ. Physiol. 2013 Aug;305(4):H506-20 PMID: 23792673   Abstract Disruption of the creatine kinase (CK) system in hearts of CK-deficient mice leads to changes in the ultrastructure and regulation of mitochondrial respiration. We expected to see similar changes in creatine-deficient mice, which lack the enzyme guanidinoacetate methyltr...

Peterson P, Kalda M, Vendelin M Am. J. Physiol., Cell Physiol. 2013 Mar;304(6):C519-31 PMID: 23255581 Abstract Sarcomere length of a cardiomyocyte is an important control parameter for physiology studies on a single cell level; for instance, its accurate determination in real time is essential for performing single cardiomyocyte contraction experiments. The aim of this work is to develop an efficient and accurate method for estimating a mean sarcomere length of a contracting cardiomy...

Schryer DW, Peterson P, Illaste A, Vendelin M PLoS Comput. Biol. 2012;8(12):e1002795 PMID: 23236266 Abstract To characterize intracellular energy transfer in the heart, two organ-level methods have frequently been employed: ³¹P − NMR inversion and saturation transfer, and dynamic ¹⁸O labeling. Creatine kinase (CK) fluxes obtained by following oxygen labeling have been considerably smaller than the fluxes determined by ³¹P − NMR saturation transfer. It has been proposed that dynamic ¹...

Illaste A, Laasmaa M, Peterson P, Vendelin M Biophys. J. 2012 Feb;102(4):739-48 PMID: 22385844 Abstract Intracellular diffusion in muscle cells is known to be restricted. Although characteristics and localization of these restrictions is yet to be elucidated, it has been established that ischemia-reperfusion injury reduces the overall diffusion restriction. Here we apply an extended version of raster image correlation spectroscopy to determine directional anisotropy and coefficients ...

Karo J, Peterson P, Vendelin M J. Biol. Chem. 2012 Mar;287(10):7467-76 PMID: 22241474 Abstract Interaction between mitochondrial creatine kinase (MtCK) and adenine nucleotide translocase (ANT) can play an important role in determining energy transfer pathways in the cell. Although the functional coupling between MtCK and ANT has been demonstrated, the precise mechanism of the coupling is not clear. To study the details of the coupling, we turned to molecular dynamics simulations. We ...

Jepihhina N, Beraud N, Sepp M, Birkedal R, Vendelin M Biophys. J. 2011 Nov;101(9):2112-21 PMID: 22067148 Abstract Intracellular diffusion restrictions for ADP and other molecules have been predicted earlier based on experiments on permeabilized fibers or cardiomyocytes. However, it is possible that the effective diffusion distance is larger than the cell dimensions due to clumping of cells and incomplete separation of cells in fiber preparations. The aim of this work was to check...

Laasmaa M, Vendelin M, Peterson P J Microsc 2011 Aug;243(2):124-40 PMID: 21323670 Abstract Although confocal microscopes have considerably smaller contribution of out-of-focus light than widefield microscopes, the confocal images can still be enhanced mathematically if the optical and data acquisition effects are accounted for. For that, several deconvolution algorithms have been proposed. As a practical solution, maximum-likelihood algorithms with regularization have been used. Howe...

Birkedal R, Shiels HA, Vendelin M Am. J. Physiol., Cell Physiol. 2006 Dec;291(6):C1148-58 PMID: 16822946 Abstract We have developed a novel method to quantitatively analyze mitochondrial positioning in three dimensions. Using this method, we compared the relative positioning of mitochondria in adult rat and rainbow trout (Oncorhynchus mykiss) ventricular myocytes. Energetic data suggest that trout, in contrast to the rat, have two subpopulations of mitochondria in their cardiomyocytes. T...

Vendelin M, Béraud N, Guerrero K, Andrienko T, Kuznetsov AV, Olivares J, Kay L, Saks VA Am. J. Physiol., Cell Physiol. 2005 Mar;288(3):C757-67 PMID: 15496480 Abstract The aim of this work was to characterize quantitatively the arrangement of mitochondria in heart and skeletal muscles. We studied confocal images of mitochondria in nonfixed cardiomyocytes and fibers from soleus and white gastrocnemius muscles of adult rats. The arrangement of intermyofibrillar mitochondria was analyzed...