Elucidation Of The Molecular Requirements Of The Low Affinity 'state' Of The Beta1-adrenoceptor
Funder
National Health and Medical Research Council
Funding Amount
$535,500.00
Summary
Beta-blockers are used for the management of cardiovascular diseases including heart failure, ischaemic heart disease and high blood pressure. Beta-blockers mostly work by blocking the effects of a naturally occuring chemical called noradrenaline. Beta-blockers can be used to prevent noradrenaline induced increases in the rate and force of human heart contraction. We have discovered that one group of beta-blockers exemplified by CGP 12177 has the remarkable property of not only being able to blo ....Beta-blockers are used for the management of cardiovascular diseases including heart failure, ischaemic heart disease and high blood pressure. Beta-blockers mostly work by blocking the effects of a naturally occuring chemical called noradrenaline. Beta-blockers can be used to prevent noradrenaline induced increases in the rate and force of human heart contraction. We have discovered that one group of beta-blockers exemplified by CGP 12177 has the remarkable property of not only being able to block beta-receptors but they can also stimulate them at higher concentrations. Thus low concentrations block the effects of noradrenaline, but higher concentrations stimulate the receptor. More puzzling is that the stimulant effects of this group of beta-blockers cannot be easily blocked. To explain this we hypothesize that human beta-receptors can exist in two different 'states'. One 'state' can be stimulated by noradrenaline and blocked by low concentrations of beta-blockers such as propranolol and CGP 12177. Another 'state' of the same receptor is resistant to blockade by beta-blockers such as propranolol but can be stimulated by beta-blockers such as CGP 12177. This project seeks to investigate the molecular basis of the beta-adrenoceptor that is responsible for stimulant effects of beta-blockers. Specifically it explores the components of the beta-adrenoceptor that are critically and uniquely important for interacting with the stimulant beta-blockers. This project is an important increment in our laboratories research program to increase our understanding of the effects of beta-blockers. Our long term goal is to be able to develop beta-blockers that can block both states of the beta-adrenoceptor to provide a more effective block of the receptor and in particular for the improved management of heart failure.Read moreRead less
Non-cardiac surgery is associated with significant risk of complications and death, particularly in elderly patients who are known to have heart disease, or who have risk factors for it (ie smoking, high blood pressure). About 11% of the Australian population are currently taking medications for heart disease or high blood pressure and about 80% have at least one risk factor for heart disease. As more than 2 million Australians have general anaesthesia for non-cardiac surgery every year, a subst ....Non-cardiac surgery is associated with significant risk of complications and death, particularly in elderly patients who are known to have heart disease, or who have risk factors for it (ie smoking, high blood pressure). About 11% of the Australian population are currently taking medications for heart disease or high blood pressure and about 80% have at least one risk factor for heart disease. As more than 2 million Australians have general anaesthesia for non-cardiac surgery every year, a substantial group of patients are therefore at risk of an adverse outcome following surgery. Despite the magnitude of this problem, however, few studies have established treatments to decrease the risk of complications and death following surgery. Beta-blockers are a group of drugs which have been used for decades in the treatment of heart disease and high blood pressure. Beta-blockers are known to improve the way the heart copes with the stress of surgery. They decrease the heart rate, make the heart more efficient at using energy and reduce the likelihood of imbalance between oxygen supply and demand. Some previous studies showed that beta-blockers may reduce the risk of heart attack and death for up to 2 years after surgery. However, other studies have shown no effect of beta-blockers on outcome. These previous studies have involved small numbers of patients who may not represent the broader population having surgery. We therefore are undertaking a large trial to definitively answer the question about whether beta-blockers improve the outcome after non-cardiac surgery in patients with, or at risk of, heart disease. Even if the effect of beta-blockers is relatively modest, because such large numbers of patients with heart disease have surgery, the overall effect on the rate of complications and death in the population could be very significant. The results of this study could have major implications for the success of, and cost of, surgery worldwide.Read moreRead less
MECHANISMS OF CEREBROVASCULAR REGULATION IN HEALTH AND DISEASE
Funder
National Health and Medical Research Council
Funding Amount
$216,430.00
Summary
Failure of the cerebral circulation to meet the brain's immediate high nutritive requirements results in stroke in just a few minutes. Stroke continues to be a major cause of death and disability, and this major medical challenge requires urgent and significant research at the basic level to better understand mechanisms of normal, and then abnormal, regulation of cerebral artery function. The project will examine the importance of a novel mechanism in regulating brain blood flow by affecting the ....Failure of the cerebral circulation to meet the brain's immediate high nutritive requirements results in stroke in just a few minutes. Stroke continues to be a major cause of death and disability, and this major medical challenge requires urgent and significant research at the basic level to better understand mechanisms of normal, and then abnormal, regulation of cerebral artery function. The project will examine the importance of a novel mechanism in regulating brain blood flow by affecting the degree of opening of the cerebral arteries. This mechanism involves activation of an enzyme, Rho-kinase, which is present in the wall of blood vessels. The applicants believe that this process plays an important role in the normal, healthy regulation of blood supply to the brain. Moreover, there are strong reasons for us to speculate that the function of this enzyme is abnormally high in two disease states that are associated with an increased risk of stroke - high blood pressure and subarachnoid haemorrhage. We will employ a variety of techniques to assess the importance of Rho-kinase in cerebral artery function in the living body, and also in isolated segments of artery. The results are expected to provide major new insight into mechanisms that regulate brain blood flow, and the knowledge gained here may lead to better therapies to prevent or treat stroke.Read moreRead less
Nox4-containing NADPH-oxidase As A Protective Enzyme In The Cerebral Circulation
Funder
National Health and Medical Research Council
Funding Amount
$515,812.00
Summary
Failure of the cerebral circulation to meet the brain's immediate high nutritive requirements results in a stroke in just a few minutes. Stroke continues to be a major cause of death and disability, and this major medical challenge requires urgent research at the basic level to better understand the processes of normal, and then abnormal, regulation of brain artery function. The project will test the importance of a newly discovered mechanism for increasing brain blood flow. This involves activa ....Failure of the cerebral circulation to meet the brain's immediate high nutritive requirements results in a stroke in just a few minutes. Stroke continues to be a major cause of death and disability, and this major medical challenge requires urgent research at the basic level to better understand the processes of normal, and then abnormal, regulation of brain artery function. The project will test the importance of a newly discovered mechanism for increasing brain blood flow. This involves activation of an enzyme, Nox4-containing NADPH-oxidase, to generate oxygen radicals which then relax the wall of blood vessels causing the arteries to let more blood through. We believe that this process plays an important role in the normal, healthy maintenance of blood supply to the brain. Furthermore, we propose that the activity of this enzyme is elevated and therefore protective in brain arteries during high blood presure - which is the major risk factor for stroke. We will specifically test whether the activity of this enzyme actually helps to limit the amount of brain death following stroke. We will use a variety of techniques to assess the importance of this enzyme in brain arteries in the living body, and also in isolated segments of brain artery from animals that are either healthy or have diseased brain arteries. The results are expected to provide major new insight into processes that help maintain brain blood flow under normal conditions and after a stroke, and the knowledge gained here should lead to safer therapies to prevent or treat stroke.Read moreRead less
Our bodies generate a hormone called angiotensin II in response to a decrease in blood pressure (or salt in our bloodstream). This hormone increases blood pressure by causing blood vessels to constrict, by making us thirsty, and by inducing salt and fluid retention via an effect on the kidneys. In some cardiovascular diseases, the generation of angiotensin II or our sensitivity to this hormone is elevated. It is therefore crucial that we understand how angiotensin II works and how its actions in ....Our bodies generate a hormone called angiotensin II in response to a decrease in blood pressure (or salt in our bloodstream). This hormone increases blood pressure by causing blood vessels to constrict, by making us thirsty, and by inducing salt and fluid retention via an effect on the kidneys. In some cardiovascular diseases, the generation of angiotensin II or our sensitivity to this hormone is elevated. It is therefore crucial that we understand how angiotensin II works and how its actions in the body are mediated. For angiotensin II to act it must first bind to a receptor. Receptors are proteins and behave like locks that are opened by the hormone keys. Thus, cellular receptors for angiotensin II are engaged and activated by increases in angiotensin II in our blood. These receptors then produce signals which initiate a response (e.g. constriction of a blood vessel). Subsequently, the receptors are switched-off to prevent over-stimulation. The experiments proposed in this application continue our investigations into how angiotensin II receptors are regulated or switched-on and -off. A major way for receptors to be turned off is for them to be ear-marked by a modification known as phosphorylation. These modified receptors are then bound by proteins termed arrestins, which as indicated by their name play a role in preventing further receptor signalling. These arrestins also help remove activated receptors from the cell surface to the inside of the cell. How arrestins interact with receptors and regulate their function is poorly understood. This application proposes experiments to investigate the molecular mechanisms of arrestin action as it relates to the angiotensin II receptor. Results from these studies will further our understanding of angiotensin II receptors and their role in cardiovascular control.Read moreRead less
Molecular Attributes And Physiological Significance Of Beta1L-adrenoceptors
Funder
National Health and Medical Research Council
Funding Amount
$754,353.00
Summary
Beta-blockers are used for the management of cardiovascular diseases including heart failure. We have discovered that one group of beta-blockers not only blocks the receptor but stimulates it. To explain this we hypothesize that human beta-adrenoceptors exist in two different 'states' , high and low. We are now determining whether 1. the low state causes progression of heart failure, 2. the molecular basis of the two states and 3. we can make new compounds to block the low state.
Perioperative Beta-blockade To Prevent Cardiac Morbidity In High-risk Patients Undergoing Surgery (The POISE Study)
Funder
National Health and Medical Research Council
Funding Amount
$189,625.00
Summary
Non-cardiac surgery is associated with significant risk of complications and death, particularly in elderly patients who are known to have heart disease, or who have risk factors for it (ie smoking, high blood pressure). About 11% of the Australian population are currently taking medications for heart disease or high blood pressure and about 80% have at least one risk factor for heart disease. As more than 2 million Australians have general anaesthesia for non-cardiac surgery every year, a subst ....Non-cardiac surgery is associated with significant risk of complications and death, particularly in elderly patients who are known to have heart disease, or who have risk factors for it (ie smoking, high blood pressure). About 11% of the Australian population are currently taking medications for heart disease or high blood pressure and about 80% have at least one risk factor for heart disease. As more than 2 million Australians have general anaesthesia for non-cardiac surgery every year, a substantial group of patients are therefore at risk of an adverse outcome following surgery. Despite the magnitude of this problem, however, few studies have established treatments to decrease the risk of complications and death following surgery. Beta-blockers are a group of drugs which have been used for decades in the treatment of heart disease and high blood pressure. Beta-blockers are known to improve the way the heart copes with the stress of surgery. They decrease the heart rate, make the heart more efficient at using energy and reduce the likelihood of imbalance between oxygen supply and demand. Some previous studies showed that beta-blockers may reduce the risk of heart attack and death for up to 2 years after surgery. However, other studies have shown no effect of beta-blockers on outcome. These previous studies have involved small numbers of patients who may not represent the broader population having surgery. We therefore propose to undertake a large trial to definitively answer the question about whether beta-blockers improve the outcome after non-cardiac surgery in patients with, or at risk of, heart disease. Even if the effect of beta-blockers is relatively modest, because such large numbers of patients with heart disease have surgery, the overall effect on the rate of complications and death in the population could be very significant. The results of this study could have major implications for the success of, and cost of, surgery worldwide.Read moreRead less
Identification Of The Pathophysiologically Relevant NADPH Oxidase Isoform In Human Cardiovascular Disease - Role Of NOX5
Funder
National Health and Medical Research Council
Funding Amount
$495,488.00
Summary
Cardiovascular diseases are the number one cause of death world-wide. Yet we do not know enough about what causes them to reliably identify and treat, let alone prevent these diseases. Therefore, this project will examine the underlying mechanisms of cardiovascular diseases, which will lead to the development of novel therapies.
Therapeutic Relevance Of AT2 Receptors In Cardiovascular Disease And Aging
Funder
National Health and Medical Research Council
Funding Amount
$519,279.00
Summary
Pharmacological modulation of the renin angiotensin system is a cornerstone of evidence-based cardiovascular therapeutics. However, their molecular mechanisms are not entirely clear and some therapeutic options have not been utilized to their full potential. The hormone angiotensin II causes both excitatory and inhibitory cardiovascular effects via distinct binding sites. Of particular importance to contemporary society is the shift in the demographic to a more aged population. In Australia in 2 ....Pharmacological modulation of the renin angiotensin system is a cornerstone of evidence-based cardiovascular therapeutics. However, their molecular mechanisms are not entirely clear and some therapeutic options have not been utilized to their full potential. The hormone angiotensin II causes both excitatory and inhibitory cardiovascular effects via distinct binding sites. Of particular importance to contemporary society is the shift in the demographic to a more aged population. In Australia in 2002, 13% of the population (~2.5 million) were aged 65 years or over, and it has been estimated that this number will increase to 18% (~4 million) by the year 2021. While lipid status and smoking are well known risk factors for cardiovascular disease, advanced age by far confers the greatest risk for cardiovascular disease. In this context, we have found a greater role of the inhibitory angiotensin II binding site in aging that may result from breakdown products of angiotensin II having their own unique effects. This project will determine the relative role of various angiotensin products, and novel compounds that may act similarly, to improve vascular tone and reverse cardiovascular disease in the elderly, hypertensive population.Read moreRead less
Role Of Extracellular Surface Residues In Agonist Activation Of The Alpha1 Adrenoceptor
Funder
National Health and Medical Research Council
Funding Amount
$414,786.00
Summary
Most modern drugs act on a class of cellular proteins known as GPCRs. Despite their importance, little is known about how agonists acting from the outside of cells produce a change in GPCR structure allowing signalling to the cell's interior. We have identified new residues on the extracellular surface of the alpha1 adrenoceptor that dramatically affect agonist responses, opening the door to understanding the molecular process of GPCR activation and the development of drugs that can target diffe ....Most modern drugs act on a class of cellular proteins known as GPCRs. Despite their importance, little is known about how agonists acting from the outside of cells produce a change in GPCR structure allowing signalling to the cell's interior. We have identified new residues on the extracellular surface of the alpha1 adrenoceptor that dramatically affect agonist responses, opening the door to understanding the molecular process of GPCR activation and the development of drugs that can target different GPCR conformations.Read moreRead less