Physiology Commons^™

Ipla2Β Overexpression In Smooth Muscle Exacerbates Angiotensin Ii-Induced Hypertension And Vascular Remodeling, Lindsay E Calderon, Shu Liu, Wen Su, Zhongwen Xie, Zhenheng Guo, Wanda Eberhard, Ming C. Gong

Physiology Faculty Publications

OBJECTIVES: Calcium independent group VIA phospholipase A₂ (iPLA₂β) is up-regulated in vascular smooth muscle cells in some diseases, but whether the up-regulated iPLA₂β affects vascular morphology and blood pressure is unknown. The current study addresses this question by evaluating the basal- and angiotensin II infusion-induced vascular remodeling and hypertension in smooth muscle specific iPLA₂β transgenic (iPLA₂β-Tg) mice.

METHOD AND RESULTS: Blood pressure was monitored by radiotelemetry and vascular remodeling was assessed by morphologic analysis. We found that the angiotensin II-induced increase in diastolic pressure was significantly higher in iPLA₂β-Tg …

Age-Associated Disruption Of Molecular Clock Expression In Skeletal Muscle Of The Spontaneously Hypertensive Rat, Mitsunori Miyazaki, Elizabeth Schroder, Stephanie E. Edelmann, Michael E. Hughes, Karl Kornacker, C. William Balke, Karyn A. Esser

Physiology Faculty Publications

It is well known that spontaneously hypertensive rats (SHR) develop muscle pathologies with hypertension and heart failure, though the mechanism remains poorly understood. Woon et al. (2007) linked the circadian clock gene Bmal1 to hypertension and metabolic dysfunction in the SHR. Building on these findings, we compared the expression pattern of several core-clock genes in the gastrocnemius muscle of aged SHR (80 weeks; overt heart failure) compared to aged-matched control WKY strain. Heart failure was associated with marked effects on the expression of Bmal1, Clock and Rora in addition to several non-circadian genes important in regulating skeletal muscle phenotype including …

A Mathematical Model Of Muscle Containing Heterogeneous Half-Sarcomeres Exhibits Residual Force Enhancement, Stuart G. Campbell, P. Chris Hatfield, Kenneth S. Campbell

Physiology Faculty Publications

A skeletal muscle fiber that is stimulated to contract and then stretched from L₁ to L₂ produces more force after the initial transient decays than if it is stimulated at L₂. This behavior has been well studied experimentally, and is known as residual force enhancement. The underlying mechanism remains controversial. We hypothesized that residual force enhancement could reflect mechanical interactions between heterogeneous half-sarcomeres. To test this hypothesis, we subjected a computational model of interacting heterogeneous half-sarcomeres to the same activation and stretch protocols that produce residual force enhancement in real preparations. Following a transient period of elevated force associated with …

Effects Of Multiple Bouts Of Long-Duration Hindlimb Unloading And Recovery On Rat Plantaris Muscle, Emily E. Jaroszewski, Kevin L. Shimkus, Yasaman Shirazi-Fard, Harry A. Hogan, James D. Fluckey

International Journal of Exercise Science: Conference Proceedings

Exposure to microgravity results in a rapid reduction of muscle mass. However, few studies exist designed to examine the effects of multiple long-term exposures to microgravity with alternating recovery periods on skeletal muscle. To determine what happens to the recovery of skeletal muscle when faced with subsequent unloading and recovery periods. Male Sprague-Dawley (6 mo) were assigned to the following groups as shown in figure 1 below: 28d hindlimb unloading (1HU), 28d HU session followed by a 56d recovery bout of normal cage ambulation at 1g (1HU+REC), 2 cycles of 28d HU with a 56d recovery period between unloadings (2HU), …

Mip/Mtmr14 And Muscle Aging, Scott K. Powers, Michael B. Reid

Physiology Faculty Publications

No abstract.

Myogenin Modulates Exercise Endurance By Altering Skeletal Muscle Metabolism, James Eric Meadows

Dissertations & Theses (Open Access)

The function of myogenic regulatory factors (MRFs) during adult life is not well understood. The requirement of one of these MRFs, myogenin (Myog), during embryonic muscle development suggests an equally important role in adult muscle. In this study, we have determined the function of myogenin during adult life using a conditional allele of Myog. In contrast to embryonic development, myogenin is not required for adult viability, and Myog-deleted mice exhibited no remarkable phenotypic changes during sedentary life. Remarkably, sedentary Myog-deleted mice demonstrated enhanced exercise endurance during involuntary treadmill running. Altered blood glucose and lactate levels in sedentary Myog-deleted mice after …

A Comparison Of Three Computer-Based Methods Used To Determine Emg Signal Amplitude, Doug Renshaw*, Matthew R. Bice†, Camille Cassidy‡, James A. Eldridge‡, Douglas W. Powell‡

International Journal of Exercise Science

Electromyography is a commonly used method to determine relative effort and neuromuscular drive to skeletal muscle. A limitation of the interpretation of EMG within the literature is the many methods used to determine the intensity of muscle activation. In the current study, ten healthy young adults performed a level walking task while EMG was recorded from the tibialis anterior, medial gastrocnemius and fibularis longus. The EMG data were rectified and smoothed using the root mean squared (RMS). Peak RMS (pRMS), mean RMS (mRMS) and integrated EMG (iEMG) were normalized to the peak value within the subject and were used to …

Genomic Profiling Of Messenger Rnas And Micrornas Reveals Potential Mechanisms Of Tweak-Induced Skeletal Muscle Wasting In Mice, Siva K. Panguluri, Shephali Bhatnagar, Akhilesh Kumar, John J. Mccarthy, Apurva K. Srivastava, Nigel G. Cooper, Robert F. Lundy, Ashok Kumar

Physiology Faculty Publications

BACKGROUND: Skeletal muscle wasting is a devastating complication of several physiological and pathophysiological conditions. Inflammatory cytokines play an important role in the loss of skeletal muscle mass in various chronic diseases. We have recently reported that proinflammatory cytokine TWEAK is a major muscle-wasting cytokine. Emerging evidence suggests that gene expression is regulated not only at transcriptional level but also at post-transcriptional level through the expression of specific non-coding microRNAs (miRs) which can affect the stability and/or translation of target mRNA. However, the role of miRs in skeletal muscle wasting is unknown.

METHODOLOGY/PRINCIPAL FINDINGS: To understand the mechanism of action of …

Passive Limb Movement Augments Ventilatory Response To Co2 Via Sciatic Inputs In Anesthetized Rats, Jianguo Zhuang, Fadi Xu, Cancan Zhang, Donald T. Frazier

Physiology Faculty Publications

Passive limb movement (PLM) in humans induces a phasic hyperpnea, but the underlying physiological mechanisms remain unclear. We asked whether PLM in anesthetized rats would produce a similar phasic hyperpnea associated with an augmented ventilatory (V̇_E) response to CO₂ that is dependent on sciatic afferents. The animals underwent 5 min threshold PLM, 3 min hypercapnia (5% CO₂), and their combination (CO₂ exposure at the end of 2^nd min of 5-min PLM) before and after bilateral transection of the sciatic nerves. We found that a threshold PLM evoked a phasic hyperpnea, similar to …

Acute And Chronic Effects Of Artificial Rearing On Rat Genioglossus Muscle, Wayne Allen Moore Jr.

Theses and Dissertations

In most mammals, nutritive suckling is critical during the early neonatal period. The genioglossus (GG) muscle in rat plays an important role in protruding the tongue for efficient suckling. The purpose of this study was to examine the contractile properties and myosin heavy chain (MHC) phenotype of the GG following an early period of artificial rearing, which reduced nutritive suckling. Beginning at three days of age Sprague-Dawley rats were fed via implanted gastric cannula until postnatal day 14 (P14). At P14, artificially reared (AR) rat pups were either placed with a lactating dam until the end of the weaning period …

A Motor And A Brake: Two Leg Extensor Muscles Acting At The Same Joint Manage Energy Differently In A Running Insect, Anna N. Ahn, Robert J. Full

All HMC Faculty Publications and Research

The individual muscles of a multiple muscle group at a given joint are often assumed to function synergistically to share the load during locomotion. We examined two leg extensors of a running cockroach to test the hypothesis that leg muscles within an anatomical muscle group necessarily manage (i.e. produce, store, transmit or absorb) energy similarly during running. Using electromyographic and video motion-analysis techniques, we determined that muscles 177c and 179 are both active during the first half of the stance period during muscle shortening. Using the in vivo strain and stimulation patterns determined during running, we measured muscle power output. …