Molecular Basis Of Ca2+-dependent Disruption Of EC-coupling And Weakness In Skeletal Muscle
Funder
National Health and Medical Research Council
Funding Amount
$530,976.00
Summary
One major cause of weakness in skeletal muscle appears to stem from damage to the mechanism controlling release of calcium ions from internal stores and consequent contraction. This project examines whether the damage is due to excessive levels of intracellular calcium ions activating enzymes that cut a particular vital molecule controlling calcium release. The findings could identify a major factor in muscle weakness in muscular dystrophy and other conditions and lead to specific therapies.
Regulation Of Calcium Release Channels (RyR2) In Healthy And Failing Hearts
Funder
National Health and Medical Research Council
Funding Amount
$337,632.00
Summary
In striated muscle, the sarcoplasmic reticulum (SR) is the calcium store from which calcium release through ryanodine receptors (RyR2) is the key determinate of muscle force. We will develop an understanding of the complex functional changes in RyR2 that underlie adaptation of the heart to physiological stress (exercise) and functional changes associated with mal-adaptation in heart failure.
Mechanisms Involved In Reduced Cardiac Contractility As A Consequence Of Growth Restriction During Fetal Development
Funder
National Health and Medical Research Council
Funding Amount
$317,810.00
Summary
Functional development of the heart muscle has been a focus of intense research over the last 40 years. Despite our current understanding of the changes in how excitation of the cardiomyocyte leads to contraction, a process broadly termed excitation-contrcation (E-C) coupling, a major model used to study paralells of human fetal development, the sheep, has not been examined in this context. As such, it remains unclear how E-C coupling evolves from the fetus to the adult. Understanding normal phy ....Functional development of the heart muscle has been a focus of intense research over the last 40 years. Despite our current understanding of the changes in how excitation of the cardiomyocyte leads to contraction, a process broadly termed excitation-contrcation (E-C) coupling, a major model used to study paralells of human fetal development, the sheep, has not been examined in this context. As such, it remains unclear how E-C coupling evolves from the fetus to the adult. Understanding normal physiology is imperative to subsequetly understand pathological states, such as interuterine growth restriction (IUGR). In Australia, the incidence of IUGR leading to low birth weight babies is 7%. IUGR is caused by maternal undernutrition, maternal smoking-drug use and placental insufficiency. It is associated with an increase in perinatal mortality, respiratory problems, SIDS and morbidity. Epidemiological studies show that low birth weight babies are also at an increased risk of cardiovascular disease, including heart failure, in adult life. To date, there is little information on the impact of fetal growth restriction on the normal development and function of the heart muscle. Understanding the impact of IUGR on heart muscle development will allow the elucidation of the underlying physiological mechanisms linking these two temporally distinct events. This mechanistic understanding will allow improved clinical management of those individuals at risk of cardiovascular disease in adult life arising from IUGR. It may also allow for early intervention strategies that can improve cardiovascular function. Therefore, we propose to examine both the normal developmental changes to E-C coupling so that we can understand how placental insufficiency leading to IUGR impairs normal heart muscle development. This will result in impaired function at a cellular level, which will ultimately manifest as an increased susceptibility of the heart to injury in later life.Read moreRead less
Manipulating Store-operated Ca2+ Entry To Improve Muscle Function In Dystrophy
Funder
National Health and Medical Research Council
Funding Amount
$516,163.00
Summary
Muscle function is regulated in a complex manner by calcium and is impaired in Duchenne muscular dystrophy (DMD). Changes in calcium regulation will be investigated in DMD patients and in an animal model using a novel approach. We will use a combination of novel experimental approaches to manipulate muscles in dystrophic mice and test for improvement in function. Results will determine the viability of a potential treatment.
Role Of Nitric Oxide And Reactive Oxygen Species In Excitation-contraction Coupling In Skeletal Muscle.
Funder
National Health and Medical Research Council
Funding Amount
$163,250.00
Summary
Excitation-contraction (E-C) coupling is a term used to broadly describe the sequence of cellular events that starts with an electrical signal at the surface membrane of a muscle cell and which then ultimately leads to muscle contraction. Although the overall sequence is known, there remain many gaps in our understanding of the mechanisms involved not only related to normal muscle function but to how this function may be impaired by excessive exercise and disease. Many cellular metabolites contr ....Excitation-contraction (E-C) coupling is a term used to broadly describe the sequence of cellular events that starts with an electrical signal at the surface membrane of a muscle cell and which then ultimately leads to muscle contraction. Although the overall sequence is known, there remain many gaps in our understanding of the mechanisms involved not only related to normal muscle function but to how this function may be impaired by excessive exercise and disease. Many cellular metabolites contribute towards the normal control of muscle contraction, while others contribute to its impairment. Reactive oxygen species (ROS), which includes nitric oxide (NO) and related molecules, are metabolic factors often referred to as cellular oxidants. They are thought to have an essential role in controlling normal muscle function. Paradoxically, they are also implicated in the impairment of muscle function associated with fatigue, disease and aging. How these molecules both control normal muscle activity and also contribute to impairment of such function remains unclear. Thus, the central aim of this project is to identify the mechanisms by which the cellular oxidants, NO and other ROS, both control normal E-C coupling in skeletal muscle fibres and how they contribute to muscle fatigue. Clearly, understanding how skeletal muscle normally contracts is essential in order to better understand how muscle function can become impaired with exercise, disease and age. The work from this study will provide insight into both normal muscle physiology and how muscles fatigue and ultimately provide new methodologies and drugs that may combat fatigue, disease and age related changes to muscle function.Read moreRead less
DHPR ? Subunit Binding To A Variably Spliced Region Of RyR1: A Role In EC Coupling And Myotonic Dystrophy
Funder
National Health and Medical Research Council
Funding Amount
$555,892.00
Summary
We have uncovered a communication pathway between two ion channel molecules in muscle cells that underlies human movement. The pathway is critical in normal mobility and is disrupted in myotonic dystrophy. We will study the molecular components of this pathway to understand normal body function and abnormal function in mytotonic dystrophy. The work will facilitate the design of drugs to relieve the mytotonic dystrophy myopathy and form new and much needed class of specific muscle relaxants.
Interactions Between The ? And ? Subunits Of The DHPR - A Missing Link In Skeletal Muscle Excitation-contraction Coupling And A Role In Sarcopenia
Funder
National Health and Medical Research Council
Funding Amount
$690,832.00
Summary
Calcium signaling is disrupted in muscle diseases, including muscle weakness in the elderly. This is a significant problem as all mobility depends on calcium signaling and its disruption can cause serious disability and death. To alleviate defective calcium signaling, the underlying molecular machinery must be fully understood, yet we have only a broad outline of the processes. We will address this problem to provide a platform for alleviating age-related muscle weakness.
Physiological And Pathological Effects Of Oxidation On Contractile Function In Skeletal Muscle
Funder
National Health and Medical Research Council
Funding Amount
$613,311.00
Summary
Reactive oxygen molecules generated within muscle fibres in normal exercise and in pathological conditions, greatly affect muscle function by altering the responsiveness of the contractile proteins. This study investigates how various oxidative stresses affect particular reactive sites on key proteins controlling muscle contraction. The findings should identify key molecular changes involved in normal activity and the role oxidation plays in chronic muscle weakness in particular conditions.