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
Professor Lewis is a molecular pharmacologist interested in discovering new venom peptides and ciguatoxins and determining how they interact with the membrane proteins they target using advanced biochemical and spectroscopic methods. Peptides of interest are then modified to improve potency and selectivity. Those with appropriate properties are patented and developed for clinical applications using approaches successfully applied to Xen2174, a conopeptide analogue I co-discovered that is now in ....Professor Lewis is a molecular pharmacologist interested in discovering new venom peptides and ciguatoxins and determining how they interact with the membrane proteins they target using advanced biochemical and spectroscopic methods. Peptides of interest are then modified to improve potency and selectivity. Those with appropriate properties are patented and developed for clinical applications using approaches successfully applied to Xen2174, a conopeptide analogue I co-discovered that is now in Phase II clinical trials for severe pain.Read moreRead less
How Does Oxygen Regulate Ca2+ Channel Function In Cardiac Myocytes?
Funder
National Health and Medical Research Council
Funding Amount
$475,517.00
Summary
Oxygen occupies a key role in cellular metabolism and function. Oxygen delivery to cells is critical and lack of oxygen such as occurs during a heart attack can be lethal. Death occurs commonly by induction of arrhythmia or a disturbance in the heart beat. The abnormal heart beat cannot enable the heart to pump blood efficiently and vital organs are then deprived.Exactly how arrhythmia is induced is not understood. The normal heart beat occurs as a result of propogation of electrical signals thr ....Oxygen occupies a key role in cellular metabolism and function. Oxygen delivery to cells is critical and lack of oxygen such as occurs during a heart attack can be lethal. Death occurs commonly by induction of arrhythmia or a disturbance in the heart beat. The abnormal heart beat cannot enable the heart to pump blood efficiently and vital organs are then deprived.Exactly how arrhythmia is induced is not understood. The normal heart beat occurs as a result of propogation of electrical signals through heart muscle cells. The electrical activity is generated and sustained by movement of salts or ions through membrane proteins known as ion channels. One of these channels, the L-type calcium channel plays a vital role in cardiac excitation and contraction. A reduction in oxygen alters the function of the L-type calcium channel. However, the exact mechanism for this is uncertain. An oxygen sensing mechanism in the cell is responsible for the regulation of channel function during hypoxia. The exact identity of the oxygen sensor is currently the centre of debate. Four hypotheses have been proposed. This proposal aims to examine in detail the four hypotheses of oxygen sensing to definitively determine the identity of the oxygen sensor. This information should increase our understanding of how calcium channels function during stressful conditions such as during a heart attack.Read moreRead less