Adenosine A1 And A3 Receptor Mediated Cardioprotection In Ischaemic Myocardium
Funder
National Health and Medical Research Council
Funding Amount
$265,698.00
Summary
Damage to the heart from coronary vascular disease causes significant morbidity and mortality in Australia. Indeed, ischaemic injury represents the single greatest cause of premature death. Moreover, due to the increasing age of our population the problem is growing - coronary artery disease affects 50% of those older than 65, contributing to an increased incidence of angina pectoris, myocardial infarction, arrhythmia, congestive heart failure, and sudden death. Protective strategies have been, ....Damage to the heart from coronary vascular disease causes significant morbidity and mortality in Australia. Indeed, ischaemic injury represents the single greatest cause of premature death. Moreover, due to the increasing age of our population the problem is growing - coronary artery disease affects 50% of those older than 65, contributing to an increased incidence of angina pectoris, myocardial infarction, arrhythmia, congestive heart failure, and sudden death. Protective strategies have been, and continue to be, developed to reduce the extent of tissue damage and minimise prolonged reductions in heart function. The success of these interventions has been mixed. This research project takes the novel approach of identifying the true roles of two receptors present in the heart (the adenosine A1 and A3 receptors) which may play a crucial role in enhancing tolerance of the heart to disease and injury. We currently do not fully understand the roles of these receptors, although preliminary findings suggest they can exert powerful protective effects during disease conditions. From a fundamental viewpoint, identifying the roles of these two receptors will significantly advance our understanding of the mechanisms of injury and protection in the heart. From a therapeutic viewpoint, this study will take us closer to the potential use of adenosine receptor-based therapy in protecting the heart from ischaemic injury.Read moreRead less
The Role Of Aquaporins In Cardiac Ischaemia And Reperfusion
Funder
National Health and Medical Research Council
Funding Amount
$412,670.00
Summary
We are studying the important clinical problem of why the heart doesn't work very well after it has been deprived of blood. This may occur during a heart attack due to coronary artery disease and during cardiac surgery when the heart is stopped. The problem affects children as well as adults undergoing surgery. The reason the heart doesn't work well is related to energy supply and tissue damage caused during the shortage of blood supply and the period soon after flow is restored. Until the heart ....We are studying the important clinical problem of why the heart doesn't work very well after it has been deprived of blood. This may occur during a heart attack due to coronary artery disease and during cardiac surgery when the heart is stopped. The problem affects children as well as adults undergoing surgery. The reason the heart doesn't work well is related to energy supply and tissue damage caused during the shortage of blood supply and the period soon after flow is restored. Until the heart recovers, inadequate pump function may cause low blood flow problems downstream in vital organs such as the brain and kidneys. Under the microscope, a common feature of affected hearts is swelling of the cells and of the energy producing parts called mitochondria. We have identified, for the first time, unique proteins that allow water to move into and around cells of the heart. These proteins are called 'aquaporins' and early results suggest they are involved in how mitochondria deal with a shortage of blood supply. Interestingly, aquaporins are also affected in diseases that affect muscle strength, and we are using what is known in these diseases to further study the role of aquaporins in the heart. Our experiments to will test heart function from the level of the cell, all the way up to the whole heart. To improve the power of our experiments, we are working with mice that lack the special water transport proteins, as a prelude to developing drug therapy for this important problem. By manipulating aquaporin levels or function, we plan to improve heart preservation during periods of no blood flow, and after surgery. This would importantly reduce the risks associated with heart attack and cardiac surgery by avoiding complications associated with poor pump function.Read moreRead less
Role Of Microparticles In Cardiac Ischemia Reperfusion Injury
Funder
National Health and Medical Research Council
Funding Amount
$55,575.00
Summary
Interventional cardiology has reduced the mortality rate associated with heart attack, unfortunately the prevalence of heart failure has subsequently increased, caused in part by reperfusion injury of previously occluded vessels. We aim to identify novel insights into the pathogenesis of IR injury in the heart, as well as the development of new approaches to prevent cardiac damage during cardiac surgery, transplantation, post-angioplasty and coronary artery stenting.
The Effect Of Ischaemia And Reperfusion On Sarcoplasmic Reticulum Calcium Handling In The Heart
Funder
National Health and Medical Research Council
Funding Amount
$236,208.00
Summary
Ischaemic heart disease is one of the most common causes of premature death in our society. Ischaemia occurs when the blood flow to the heart is obstructed so that oxygen cannot get to the muscle cells and metabolic waste products cannot be washed away. During ischaemia the concentration of free calcium within a cardiac muscle cell increases, and when blood flow is returned to the muscle this calcium concentration can increase further to very high levels. It is this change in calcium that is res ....Ischaemic heart disease is one of the most common causes of premature death in our society. Ischaemia occurs when the blood flow to the heart is obstructed so that oxygen cannot get to the muscle cells and metabolic waste products cannot be washed away. During ischaemia the concentration of free calcium within a cardiac muscle cell increases, and when blood flow is returned to the muscle this calcium concentration can increase further to very high levels. It is this change in calcium that is responsible for the reduced muscle force and abnormal cardiac rhythm that are the main cause of death. Cardiac muscle cells contain an intracellular compartment called the sarcoplasmic reticulum (SR). Under normal conditions the SR stores large amounts of calcium in order to maintain a low concentration of calcium free within the cell. However, even in a resting cell, calcium can escape from the SR through channels in SR membrane. We are using a state-of-the-art microscope to visualize these tiny packets of calcium, termed calcium sparks, as they travel through the SR membrane. If the number of calcium sparks increases, the amount of calcium being released from the SR also increases. We are studying what happens to calcium sparks, and therefore SR calcium release, during ischaemic heart disease. We are also examining the effect of ischaemic heart disease on the concentration of calcium within the SR and the activity of the transporters that pump calcium back into the SR. We hope to show that a change in the way the SR regulates calcium contributes to ischaemic damage. Understanding how changes in SR function alter muscle force and cardiac rhythm will help in the development of drugs to protect against ischaemic damage.Read moreRead less
The Importance Of P38 MAPK Signalling In Aging-Related Ischaemic Intolerance And Failed Cardioprotection
Funder
National Health and Medical Research Council
Funding Amount
$496,302.00
Summary
Ischaemic heart disease is the leading cause of death in Australia, and will rise in coming years with the aging of our population. Our research shows aged hearts become less resistant to damage during ischaemia-heart attack, and insensitive to normally beneficial therapies. This project will identify molecular changes responsible for these changes. By understanding how age impairs the hearts defences, it may be possible to improve therapy of ischaemic heart disease in older patients.
C-JUN TARGETING STRATEGIES AS NOVEL CARDIOPROTECTIVE AGENTS IN ISCHAEMIA-REPERFUSION INJURY
Funder
National Health and Medical Research Council
Funding Amount
$361,148.00
Summary
Acute myocardial infarction (AMI) and its sequelae are an increasing problem in terms of morbidity, mortality and healthcare costs in Australia and the industrialised world; in the USA this is estimated annually at 900,000 and 225,000 patients and US$60 billion, respectively. Current treatment for AMI includes mechanical (percutaneous coronary intervention) or thrombolytic therapy; however, these approaches are directed primarily at epicardial arteries rather than the myocardium and are, therefo ....Acute myocardial infarction (AMI) and its sequelae are an increasing problem in terms of morbidity, mortality and healthcare costs in Australia and the industrialised world; in the USA this is estimated annually at 900,000 and 225,000 patients and US$60 billion, respectively. Current treatment for AMI includes mechanical (percutaneous coronary intervention) or thrombolytic therapy; however, these approaches are directed primarily at epicardial arteries rather than the myocardium and are, therefore, suboptimal. Strategies aimed at directly protecting cardiomyocytes from ischaemia-reperfusion injury, reducing leukocyte recruitment and myocardial cell death, would complement current approaches restoring epicardial artery flow and are keenly sought. This project will demonstrate the capacity of two separate gene-silencing strategies (DNAzymes and siRNA to suppress the expression of the immediate-early gene, c-Jun in cardiomyocytes and reduce infarct size, left ventricular dysfunction, apoptosis, inflammation, production of reactive oxygen species, angiogenesis and fibrosis in the injured rat myocardium. It will also shed light on the molecular mechanisms underlying c-Jun-mediated myocardial inflammation. As such, these studies will provide important proof of principle evidence for these small molecule nucleic acid agents as potential therapeutic tools as cardioprotective agents in ischaemia-reperfusion injury.Read moreRead less
Structural And Functional Alterations Of Sarcomeric Proteins In Reperfused Myocardium
Funder
National Health and Medical Research Council
Funding Amount
$271,786.00
Summary
Coronary artery disease remains the major cause of mortality for the adult population in our society. Despite the advances of coronary artery bypass surgery and medical treatment for reperfusion of occluded coronary arteries, the problem of impaired pump function of the heart remains a major obstacle. Although blood flow can be restored to the jeopardised heart muscle by either clot dissolving drugs, balloon angioplasty, or coronary artery surgery, the heart muscle may not regain pump function f ....Coronary artery disease remains the major cause of mortality for the adult population in our society. Despite the advances of coronary artery bypass surgery and medical treatment for reperfusion of occluded coronary arteries, the problem of impaired pump function of the heart remains a major obstacle. Although blood flow can be restored to the jeopardised heart muscle by either clot dissolving drugs, balloon angioplasty, or coronary artery surgery, the heart muscle may not regain pump function for days to weeks after the event. This delayed recovery of pump function, known as myocardial stunning, can lead to heart failure and slow down a patient's recovery from heart surgery or heart attack. The cause of this myocardial stunning is unknown. We suggest that stunning results from damage to essential proteins in the contractile apparatus of the heart, which requires a prolonged time period for repair. This project aims to identify the site and extent of protein damage occurring in the heart following interruption and subsequent restoration of cardiac blood flow. In concert with this, we seek to determine the mechanism of protein damage. The findings of this project should allow us to subsequently investigate new treatment approaches for acute pump dysfunction in patients with ischaemic heart disease.Read moreRead less
Adenosinergic Control Of Cell Death In Ischaemic-Reperfused Myocardium
Funder
National Health and Medical Research Council
Funding Amount
$339,375.00
Summary
Despite a decline in death rates due to heart disease over the last decade, cardiovascular disease remains a major cause of premature death and disability in our population. During a heart attack the single most important factor determining outcome is the extent of cell death. Thus, the most valuable thing we can do is reduce the numbers of cardiac cells which die during and following heart attack. In recent years we have learned that cell death during a heart attack occurs via an active process ....Despite a decline in death rates due to heart disease over the last decade, cardiovascular disease remains a major cause of premature death and disability in our population. During a heart attack the single most important factor determining outcome is the extent of cell death. Thus, the most valuable thing we can do is reduce the numbers of cardiac cells which die during and following heart attack. In recent years we have learned that cell death during a heart attack occurs via an active process termed apoptosis (or programmed cell death). Novel therapeutic strategies for limiting cardiac apoptosis are highly desirable. This research project will examine the possibility that a locally generated chemical (termed adenosine) can very effectively reduce this form of death via multiple pathways. By understanding how one of the heart's own intrinsic defense mechanisms functions (the adenosine system), it may be possible to design new therapeutic approaches for treatment and management of ischaemic heart disease.Read moreRead less
Does Remote Ischemic Preconditioning Induce Protective Mitochondrial Function In Congenital Heart Defect Repair Surgery?
Funder
National Health and Medical Research Council
Funding Amount
$142,759.00
Summary
The body's own protective mechanism against injury due to reduced blood flow (ischemic preconditioning) has been studied for over 2 decades, yet the clinical benefits have not been realised until recently . We have previously shown that this innate protection can be induced without drugs in children having heart surgery. We will extend these findings to determine the mechanism of protection, develop a method to monitor this in blood cells and see if this is related to post-operative outcomes.
Enkephalin Metabolism In Cardiac Ischemia, Heart Failure And Cardiac Surgery
Funder
National Health and Medical Research Council
Funding Amount
$327,037.00
Summary
It has recently been discovered in animal studies that heart muscle can make its own opioid proteins. Previously, it was thought that only nerves made and released opioids. We have recently found that a class of opioids called enkephalins are made and then depleted from the heart during the stress of oxygen and nutrient deprivation. Enkephalins have been found to have potent metabolic effects on the heart. Previous work has shown that opioids can protect the heart against injury incurred during ....It has recently been discovered in animal studies that heart muscle can make its own opioid proteins. Previously, it was thought that only nerves made and released opioids. We have recently found that a class of opioids called enkephalins are made and then depleted from the heart during the stress of oxygen and nutrient deprivation. Enkephalins have been found to have potent metabolic effects on the heart. Previous work has shown that opioids can protect the heart against injury incurred during disease that restricts energy and oxygen supply to the blood vessels and heart. We wish to demonstrate this for the first time in human heart, and we will explore whether the production of enkephalins is altered by the stresses of cardiac surgery and heart failure. Understanding how the human heart attempts to protect itself in disease and how enkephalins work under these conditions, may prove valuable in the development of new drug therapy with synthetic drugs which mimic the action of enkephalins for heart protection during cardiac surgery, heart transplantation and ischemic heart disease. We will test whether specific enkephalins may be used to improve donor heart viability for transplantation by improving the duration and quality of preservation during storage. Understanding what happens to enkephalin production and metabolism in the failing hearts of patients may allow us to find new therapeutic targets in heart failure.Read moreRead less