Brenda Russell - Academia.edu (original) (raw)

Papers by Brenda Russell

Journal of Cardiovascular Nursing, Mar 1, 2009

Pflügers Archiv: European Journal of Physiology, Feb 11, 2011

Biochemical and Biophysical Research Communications, 2013

Biomechanics and Modeling in Mechanobiology, Oct 2, 2014

Cytoskeleton, Aug 1, 2018

Journal of Muscle Research and Cell Motility, Oct 1, 2015

FEBS Letters, Aug 8, 2007

Biophysical Journal, Feb 1, 2018

Biomedical Microdevices, Jul 29, 2010

Canadian Journal of Physiology and Pharmacology, Nov 1, 2016

Journal of Ultrastructure Research, 1976

Stereological techniques are used to obtain quantitative information from electron micrographs fr... more Stereological techniques are used to obtain quantitative information from electron micrographs from 300 fibers of skeletal muscle from the adult guinea pig. Ultrastructural parameters measured include Z line width, volume of mitochondria, volume and surface area of tsystem, terminal cisternae, and sarcoplasmic reticulum. Histograms, scattergrams, and statistical discriminant analysis are used to analyze the data. The whole fiber population can be separated with 90% success rate into the red and white vastus muscles and the soleus muscle, which are physiologically fast and slow, respectively. The soleus fibers have a Z line wider than 1100 A and smaller amounts of t-system and terminal cisternae than the vastus fibers. The mitochondrial volume of the vastus fibers shows a continuous distribution over a large range (0.1-15%), with the white vastus fibers at the lower end and the red vastus fibers at the higher end.

Cellular Signalling, Aug 1, 2016

The mechanotransduction signaling pathways initiated in heart muscle by increased mechanical load... more The mechanotransduction signaling pathways initiated in heart muscle by increased mechanical loading are known to lead to long-term transcriptional changes and hypertrophy, but the rapid events for adaptation at the sarcomeric level are not fully understood. The goal of this study was to test the hypothesis that actin filament assembly during cardiomyocyte growth is regulated by posttranslational modifications (PTMs) of CapZβ1. In rapidly hypertrophying neonatal rat ventricular myocytes (NRVMs) stimulated by phenylephrine (PE), two-dimensional gel electrophoresis (2DGE) of CapZβ1 revealed a shift toward more negative charge. Consistent with this, mass spectrometry identified CapZβ1 phosphorylation on serine-204 and acetylation on lysine-199, two residues which are near the actin binding surface of CapZβ1. Ectopic expression of dominant negative PKCε (dnPKCε) in NRVMs blunted the PE-induced increase in CapZ dynamics, as evidenced by the kinetic constant (Kfrap) of fluorescence recovery after photobleaching (FRAP), and concomitantly reduced phosphorylation and acetylation of CapZβ1. Furthermore, inhibition of class I histone deacetylases (HDACs) increased lysine-199 acetylation on CapZβ1, which increased K frap of CapZ and stimulated actin dynamics. Finally, we show that PE treatment of NRVMs results in decreased binding of HDAC3 to myofibrils, suggesting a signal-dependent mechanism for the regulation of sarcomere-associated CapZβ1 acetylation. Taken together, this dual regulation through phosphorylation and acetylation of CapZβ1 provides a novel model for the regulation of myofibril growth during cardiac hypertrophy.

Comprehensive Physiology, 1983

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Tissue and Cell, 1975

During fixation of single muscles fibers with glutaraldehyde, the volume of the fiber shrinks 20%... more During fixation of single muscles fibers with glutaraldehyde, the volume of the fiber shrinks 20%, recovers in rinse and osmium tetroxide to near normal volume and shrinks 20% again when staining with uranyl acetate. This suggest that osmotic properties of membranes may not have been completely lost during fixation, post-fixation and en bloc staining. Dehydration in ethanol and propylene oxide produces a further 10% shrinkage in volume. Infiltration and embedding with Epon causes an additional 15% change in volume. This gives a total shrinkage in volume of 45% which is nearly twice that of the apparent shrinkage in the volume of the myosin lattice as determined by electron microscopy.

Proceedings of the Royal Society B: Biological Sciences, 1983

Purkinje strands from both ventricles of adult mongrel dogs were excised, and electrical properti... more Purkinje strands from both ventricles of adult mongrel dogs were excised, and electrical properties were studied by the voltage-clamp technique. The strands were then examined with light and electron microscopy and structural properties were analysed by morphometric techniques. The canine Purkinje strand contains (by volume) about 28% myocyte and 55% dense outer connective tissue. The remainder of the volume is taken up by the inner shell of loosely packed connective tissue within 10 μm of a myocyte membrane. These volume fractions vary considerably from one strand to another. Clefts less than 10 μm wide occupy 18% of the myocyte volume and clefts less than 1 μm wide occupy 1%. The membrane surface area of the myocytes can be divided into three categories by reference to the size of the adjacent cleft. About 47.8% of the membrane surface area faces clefts wider than 1 μm, another 22.2% faces clefts between 0.1 and 1 μm wide, and the final 30% faces clefts less than 0.1 μm wide. The ...

FEBS Journal, Aug 8, 2023

Loss of myocardial mass in a neonatal rat cardiomyocyte culture is studied to determine whether t... more Loss of myocardial mass in a neonatal rat cardiomyocyte culture is studied to determine whether there is a distinguishable cellular response based on the origin of mechano‐signals. The approach herein compares the sarcomeric assembly and disassembly processes in heart cells by imposing mechano‐signals at the interface with the extracellular matrix (extrinsic) and at the level of the myofilaments (intrinsic). Experiments compared the effects of imposed internal (inside/out) and external (outside/in) loading and unloading on modifications in neonatal rat cardiomyocytes. Unloading of the cellular substrate by myosin inhibition (1μM mavacamten), or cessation of cyclic strain (1 Hz, 10% strain) after preconditioning, led to significant disassembly of sarcomeric α‐actinin by 6 hrs. In myosin inhibition, this was accompanied by redistribution of intracellular poly‐ubiquitin K48 to the cellular periphery relative to the poly‐ubiquitin K48 reservoir at the I‐band. Moreover, loading and unloading of the cellular substrate led to a three‐fold increase in post translational modifications (PTMs) when compared to the myosin‐specific activation or inhibition. Specifically, phosphorylation increased with loading while ubiquitination increased with unloading, which may involve ERK1/2 and FAK activation. The identified PTMs, including ubiquitination, acetylation, and phosphorylation, are proposed to modify internal domains in α‐actinin to increase its propensity to bind F‐actin. These results demonstrate a link between mechanical feedback and sarcomere protein homeostasis via PTMs of α‐actinin that exemplify how cardiomyocytes exhibit differential responses to the origin of force. The implications of sarcomere regulation governed by PTMs of α‐actinin are discussed with respect to cardiac atrophy and heart failure.