Physiology Commons^™

In Vivo Potentiation Of Muscle Torque Is Enhanced In Female Mice Through Estradiol-Estrogen Receptor Signaling, Gengyun Le, Cory W. Baumann, Dawn A. Lowe, Gordon L. Warren

Biology Faculty Publications

Estradiol affects several properties of skeletal muscle in females including strength. Here, we developed an approach to measure in vivo posttetanic twitch potentiation (PTP) of the anterior crural muscles of anesthetized mice and tested the hypothesis that 17b-estradiol (E2) enhances PTP through estrogen receptor (ER) signaling. Peak torques of potentiated twitches were 40%–60% greater than those of unpotentiated twitches and such PTP was greater in ovary-intact mice, or ovariectomized (Ovx) mice treated with E2, compared with Ovx mice (P < 0.047). PTP did not differ between mice with and without ERa ablated in skeletal muscle fibers (P = 0.347). Treatment of ovary-intact and Ovx mice with ERb antagonist and agonist (PHTPP and DPN, respectively) did not affect PTP (P = 0.258). Treatment with G1, an agonist of the G protein-coupled estrogen receptor (GPER), significantly increased PTP in Ovx mice from 41 ± 10% to 66 ± 21% (means ± SD; P = 0.034). Collectively, these data indicate that E2 signals through GPER, and not ERa or ERb, in skeletal muscles of female mice to augment an in vivo parameter of strength, namely, PTP.

Rapid And Direct Action Of Lipopolysaccharide (Lps) On Skeletal Muscle Of Larval Drosophila, Rachel Potter, Alexis Meade, Samuel Potter, Robin L. Cooper

Biology Faculty Publications

The endotoxin lipopolysaccharide (LPS) from Gram-negative bacteria exerts a direct and rapid effect on tissues. While most attention is given to the downstream actions of the immune system in response to LPS, this study focuses on the direct actions of LPS on skeletal muscle in Drosophila melanogaster. It was noted in earlier studies that the membrane potential rapidly hyperpolarizes in a dose-dependent manner with exposure to LPS from Pseudomonas aeruginosa and Serratia marcescens. The response is transitory while exposed to LPS, and the effect does not appear to be due to calcium-activated potassium channels, activated nitric oxide synthase …

Scaling Of Computed Tomography Body Composition To Height: Relevance Of Height-Normalized Indices In Patients With Colorectal Cancer, Justin C. Brown, Steven B. Heymsfield, Bette J. Caan

School of Medicine Faculty Publications

Background: Body weight scales to height with a power of ≈2 (weight/height2), forming the basis of body mass index (BMI). The corresponding scaling of body composition measured by abdominal computed tomography (CT) to height has not been established. The objective of this analysis was to quantify the scaling of body composition measured by a single-slice axial abdominal CT image (skeletal muscle, and visceral, subcutaneous, and total adipose tissue) to height in patients with colorectal cancer (CRC). Methods: This cross-sectional study included non-Hispanic white males and females, aged 18–80 years, who were diagnosed with stage I–III CRC at an integrated health …

Lat1 Protein Content Increases Following 12 Weeks Of Resistance Exercise Training In Human Skeletal Muscle, Paul A. Roberson, Christopher Brooks Mobley, Matthew A. Romero, Cody T. Haun, Shelby C. Osburn, Petey W. Mumford, Christopher G. Vann, Rory A. Greer, Arny A. Ferrando, Michael D. Roberts

Physiology Faculty Publications

Introduction: Amino acid transporters are essential for cellular amino acid transport and promoting protein synthesis. While previous literature has demonstrated the association of amino acid transporters and protein synthesis following acute resistance exercise and amino acid supplementation, the chronic effect of resistance exercise and supplementation on amino acid transporters is unknown. The purpose herein was to determine if amino acid transporters and amino acid metabolic enzymes were related to skeletal muscle hypertrophy following resistance exercise training with different nutritional supplementation strategies.

Methods: 43 college-aged males were separated into a maltodextrin placebo (PLA, n = 12), leucine (LEU, n = 14), …

Postprandial Microvascular Blood Flow In Skeletal Muscle: Similarities And Disparities To The Hyperinsulinaemic-Euglycaemic Clamp, Katherine M. Roberts-Thomson, Andrew C. Betik, Dino Premilovac, Stephen Rattigan, Stephen M. Richards, Renee M. Ross, Ryan D. Russell, Gunveen Kaur, Lewan Parker, Michelle A. Keske

Health & Human Performance Faculty Publications and Presentations

Skeletal muscle contributes to ~40% of total body mass and has numerous important mechanical and metabolic roles in the body. Skeletal muscle is a major site for glucose disposal following a meal. Consequently, skeletal muscle plays an important role in postprandial blood glucose homeostasis. Over the past number of decades, research has demonstrated that insulin has an important role in vasodilating the vasculature in skeletal muscle in response to an insulin infusion (hyperinsulinaemic-euglycaemic clamp) or following the ingestion of a meal. This vascular action of insulin is pivotal for glucose disposal in skeletal muscle, as insulin-stimulated vasodilation increases the delivery …

A Critical Evaluation Of The Biological Construct Skeletal Muscle Hypertrophy: Size Matters But So Does The Measurement, Cody T. Haun, Christopher G. Vann, Brandon M. Roberts, Andrew D. Vigotsky, Brad J. Schoenfeld, Michael D. Roberts

Publications and Research

Skeletal muscle is highly adaptable and has consistently been shown to morphologically respond to exercise training. Skeletal muscle growth during periods of resistance training has traditionally been referred to as skeletal muscle hypertrophy, and this manifests as increases in muscle mass, muscle thickness, muscle area, muscle volume, and muscle fiber cross-sectional area (fCSA). Delicate electron microscopy and biochemical techniques have also been used to demonstrate that resistance exercise promotes ultrastructural adaptations within muscle fibers. Decades of research in this area of exercise physiology have promulgated a widespread hypothetical model of training-induced skeletal muscle hypertrophy; specifically, fCSA increases are accompanied by …

Physiological Differences Between Low Versus High Skeletal Muscle Hypertrophic Responders To Resistance Exercise Training: Current Perspectives And Future Research Directions, Michael D. Roberts, Cody T. Haun, Christopher B. Mobley, Petey W. Mumford, Matthew A. Romero, Paul A. Roberson, Christopher G. Vann, John J. Mccarthy

Physiology Faculty Publications

Numerous reports suggest there are low and high skeletal muscle hypertrophic responders following weeks to months of structured resistance exercise training (referred to as low and high responders herein). Specifically, divergent alterations in muscle fiber cross sectional area (fCSA), vastus lateralis thickness, and whole body lean tissue mass have been shown to occur in high versus low responders. Differential responses in ribosome biogenesis and subsequent protein synthetic rates during training seemingly explain some of this individual variation in humans, and mechanistic in vitro and rodent studies provide further evidence that ribosome biogenesis is critical for muscle hypertrophy. High responders may …

Biology Of Exosomes And Their Microrna Cargos In Human And Bovine Milk, Amy Lynn Leiferman

College of Education and Human Sciences: Dissertations, Theses, and Student Research

Exosomes are small, cargo-containing vesicles secreted by cells to facilitate intercellular communication. Of exosome cargos, microRNAs are especially interesting because of their involvement in gene regulation. Recently, our lab has shown that exosomes and their microRNA cargo are absorbed through the diet and elicit effects exogenously. Human and animal milk contain exosomes, which may have implications in infant and adult nutrition. There is evidence that bovine milk exosomes enhance growth of murine C2C12 myotube cell cultures, but whether this translates to muscle in vivo is unknown. The USDA National Nutrient Database for Standard Reference is lacking up-to-date information about human …

Transcriptional Profiling Reveals Extraordinary Diversity Among Skeletal Muscle Tissues, Erin E. Terry, Xiping Zhang, Christy Hoffmann, Laura D. Hughes, Scott A. Lewis, Jiajia Li, Matthew J. Wallace, Lance A. Riley, Collin M. Douglas, Miguel A. Gutierrez-Monreal, Nicholas F. Lahens, Ming C. Gong, Francisco H. Andrade, Karyn A. Esser, Michael E. Hughes

Physiology Faculty Publications

Skeletal muscle comprises a family of diverse tissues with highly specialized functions. Many acquired diseases, including HIV and COPD, affect specific muscles while sparing others. Even monogenic muscular dystrophies selectively affect certain muscle groups. These observations suggest that factors intrinsic to muscle tissues influence their resistance to disease. Nevertheless, most studies have not addressed transcriptional diversity among skeletal muscles. Here we use RNAseq to profile mRNA expression in skeletal, smooth, and cardiac muscle tissues from mice and rats. Our data set, MuscleDB, reveals extensive transcriptional diversity, with greater than 50% of transcripts differentially expressed among skeletal muscle tissues. We detect …

Acute Resistance Exercise Induces Sestrin2 Phosphorylation And P62 Dephosphorylation In Human Skeletal Muscle, Nina Zeng, Randall F. D'Souza, Vandre C. Figueiredo, James F. Markworth, Llion A. Roberts, Jonathan M. Peake, Cameron J. Mitchell, David Cameron-Smith

Center for Muscle Biology Faculty Publications

Sestrins (1, 2, 3) are a family of stress-inducible proteins capable of attenuating oxidative stress, regulating metabolism, and stimulating autophagy. Sequestosome1 (p62) is also a stress-inducible multifunctional protein acting as a signaling hub for oxidative stress and selective autophagy. It is unclear whether Sestrin and p62^Ser403 are regulated acutely or chronically by resistance exercise (RE) or training (RT) in human skeletal muscle. Therefore, the acute and chronic effects of RE on Sestrin and p62 in human skeletal muscle were examined through two studies. In Study 1, nine active men (22.1 ± 2.2 years) performed a bout of single-leg strength …

Effects Of Leucine Supplementation And Resistance Training On Myopathy Of Diabetic Rats, Carlos Eduardo C. Martins, Vanessa B. De S. Lima, Brad J. Schoenfeld, Julio Tirapegui

Publications and Research

Leucine supplementation and resistance training positively influence the protein translation process and the cell signaling mTOR (mammalian target of rapamycin) pathway that regulates muscle protein balance and muscle remodeling, and thus may be therapeutic to diabetic myopathy. However, the effect of a combined intervention has not been well studied. Forty male Wistar rats were divided into five groups, control (C), diabetic control (D), diabetic + trained (DT), diabetic + L-leucine (DL), diabetic + L-leucine + trained (DLT). The supplementation of 5% leucine in chow, and resistance training were conducted for 8 weeks postweaning of rats. The extensor digitorum longus was …

Micrornas, Heart Failure, And Aging: Potential Interactions With Skeletal Muscle, Kevin A. Murach, John J. Mccarthy

Center for Muscle Biology Faculty Publications

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression by targeting mRNAs for degradation or translational repression. MiRNAs can be expressed tissue specifically and are altered in response to various physiological conditions. It has recently been shown that miRNAs are released into the circulation, potentially for the purpose of communicating with distant tissues. This manuscript discusses miRNA alterations in cardiac muscle and the circulation during heart failure, a prevalent and costly public health issue. A potential mechanism for how skeletal muscle maladaptations during heart failure could be mediated by myocardium-derived miRNAs released to the circulation is presented. An overview …

Blubber Transciptome Response To Acute Stress Axis Activation Involves Transient Charges In Adipogenesis And Lipolysis In Fast-Adapted Marine Mammal, J. I. Khudyakov, C. D. Champagne, L. M. Meneghetti, D. E. Crocker

Biological Sciences Faculty Publications

Stress can compromise an animal's ability to conserve metabolic stores and participate in energy-demanding activities that are critical for fitness. Understanding how wild animals, especially those already experiencing physiological extremes (e.g. fasting), regulate stress responses is critical for evaluating the impacts of anthropogenic disturbance on physiology and fitness, key challenges for conservation. However, studies of stress in wildlife are often limited to baseline endocrine measurements and few have investigated stress effects in fasting-adapted species. We examined downstream molecular consequences of hypothalamic-pituitary-adrenal (HPA) axis activation by exogenous adrenocorticotropic hormone (ACTH) in blubber of northern elephant seals due to the ease of …

The Endogenous Molecular Clock Orchestrates The Temporal Separation Of Substrate Metabolism In Skeletal Muscle, Brian A. Hodge, Yuan Wen, Lance A. Riley, Xiping Zhang, Jonathan H. England, Brianna D. Harfmann, Elizabeth A. Schroder, Karyn A. Esser

Physiology Faculty Publications

BACKGROUND: Skeletal muscle is a major contributor to whole-body metabolism as it serves as a depot for both glucose and amino acids, and is a highly metabolically active tissue. Within skeletal muscle exists an intrinsic molecular clock mechanism that regulates the timing of physiological processes. A key function of the clock is to regulate the timing of metabolic processes to anticipate time of day changes in environmental conditions. The purpose of this study was to identify metabolic genes that are expressed in a circadian manner and determine if these genes are regulated downstream of the intrinsic molecular clock by …

Proteomic Analysis Of Media From Lung Cancer Cells Reveals Role Of 14-3-3 Proteins In Cachexia, Julie B. Mclean, Jennifer S. Moylan, Erin M. Wolf Horrell, Francisco H. Andrade

Physiology Faculty Publications

Aims: At the time of diagnosis, 60% of lung cancer patients present with cachexia, a severe wasting syndrome that increases morbidity and mortality. Tumors secrete multiple factors that contribute to cachectic muscle wasting, and not all of these factors have been identified. We used Orbitrap electrospray ionization mass spectrometry to identify novel cachexia-inducing candidates in media conditioned with Lewis lung carcinoma cells (LCM).

Results: One-hundred and 58 proteins were confirmed in three biological replicates. Thirty-three were identified as secreted proteins, including 14-3-3 proteins, which are highly conserved adaptor proteins known to have over 200 binding partners. We confirmed the …

The Role Of Mmp-2, 9, And 13, In The Regulation Of Skeltal Muscle Hypertrophy Following Functional Overload, Reilly Fitzpatrick

Summer Research

PURPOSE: Skeletal muscle is the most abundant tissue in vertebrates that functions primarily to generate locomotion, and exhibits a high degree of structural and functional plasticity that is largely dependent on the level of activity placed on it. Recent studies have shown that a family of enzymes known as matrix metalloproteinases (MMPs) play an important role in regulating this plasticity. Specifically, MMP-2 and MMP-9 degrade components of the extracellular matrix (ECM) surrounding muscle fiber during periods of growth and repair. However, the mechanisms by which these MMPs mediate this response and how each contributes to muscle repair and remodeling remains …

Mitochondria Dysfunction In Lung Cancer-Induced Muscle Wasting In C2c12 Myotubes, Julie B. Mclean, Jennifer S. Moylan, Francisco H. Andrade

Physiology Faculty Publications

Aims: Cancer cachexia is a syndrome which results in severe loss of muscle mass and marked fatigue. Conditioned media from cachexia-inducing cancer cells triggers metabolic dysfunction in skeletal muscle, including decreased mitochondrial respiration, which may contribute to fatigue. We hypothesized that Lewis lung carcinoma conditioned medium (LCM) would impair the mitochondrial electron transport chain (ETC) and increase production of reactive oxygen species, ultimately leading to decreased mitochondrial respiration. We incubated C2C12 myotubes with LCM for 30 min, 2, 4, 24 or 48 h. We measured protein content by western blot; oxidant production by 2′,7′-dichlorofluorescin diacetate (DCF), 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF), and …

Do Hypothermic Tissue Tolerances Limit Torpor Expression?, Clark J. Cotton, Henry J. Harlow

Biology Faculty Publications

1. Arrest temperatures and Q₁₀ values for extensor digitorum longus (EDL), soleus, trabecula, and jejunum muscle twitch strength, contraction time, and 0.5 relaxation time were calculated for a deep torpor hibernator, white-tailed prairie dog (WTPD) (Cynomys leucurus), a shallow torpor hibernator, black-tailed prairie dog (BTPD) (Cynomys ludovicianus), and a non-hibernator, lab rat (Rattus norvegicus) to test the hypothesis that tissue temperature tolerances limit the depth of expressed torpor.

2. There were no temperature tolerance differences between the tissues of the two species of hibernators. Both hibernating species had arrest temperatures and Q_{10 …}