Salt And Cardiovascular Disease: Does Acute Salt-Sensitivity Convey Greater Cardiovascular Risk?
Funder
National Health and Medical Research Council
Funding Amount
$597,578.00
Summary
Salt intake of Australian adults is 10X more than required. Further, salt intake in very young children is alarmingly high secondary to high consumption of salty snacks and processed food. High dietary salt intake has been associated with increased cardiovascular disease and death. We will examine the cardiovascular risks for adults and children on a high salt diet and examine whether switching to a low salt diet ameliorates the high blood pressure and heart disease caused by high salt diets
Human Muscle Stretch Reflexes: The Effects Of Stimulus Properties, Muscle State And Subject Intention
Funder
National Health and Medical Research Council
Funding Amount
$170,604.00
Summary
The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch ....The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch modulates the muscle activity such that an increase in contraction of the muscle opposes the stretch and defends the position of the joint against the external disturbance. This is the everyday situation in which stretch reflexes operate. Despite extensive investigation for over a hundred years, there is still no consensus among researchers about the behaviour of stretch reflexes nor about their role in the control of movement. Even the demarcation of reflex from voluntary muscle activity is not always certain. One of the outstanding features of stretch reflexes is the variability of their behaviour, which depends on the particular muscle involved, its level of contraction, the type of stretch and the task in which the person is engaged. This variability has made it difficult for researchers to determine the role of reflexes in the control of movement. In order to study stretch reflex behaviour in human subjects, we will measure the electrical activity of elbow muscles, the elbow position and the force generated at the joint under a variety of conditions. A series of five experiments will investigate specific unresolved issues such as the effect of subject intention on the modulation of muscle activity and how altered modulation of muscle activity may change the stiffness of our limbs. The objective of the experimental series is to fill in important gaps in the picture of the behaviour of the stretch reflex.Read moreRead less
Hypothalamic Regulation Of Cardiovascular Function In Hypertension And Stress
Funder
National Health and Medical Research Council
Funding Amount
$570,880.00
Summary
Blood pressure is controlled to a large extent by nerves, known as sympathetic nerves, that supply the heart and blood vessels. The activity of sympathetic nerves is commonly increased in people with high blood pressure, particularly younger patients. This has the effect of constricting blood vessels and increasing heart rate, which places an additional load on the heart, and increasing the risk of heart attacks and stroke. Sympathetic nerves are also activated strongly in response to stress. In ....Blood pressure is controlled to a large extent by nerves, known as sympathetic nerves, that supply the heart and blood vessels. The activity of sympathetic nerves is commonly increased in people with high blood pressure, particularly younger patients. This has the effect of constricting blood vessels and increasing heart rate, which places an additional load on the heart, and increasing the risk of heart attacks and stroke. Sympathetic nerves are also activated strongly in response to stress. In some people stress can trigger an extreme reaction, called a panic disorder, characterised by intense sympathetic activation, which also increases the risk of heart attacks. A region in the brain called the hypothalamus plays a key role in generating these increases in sympathetic nerve activity. This project aims first to identify the precise region or regions in the hypothalamus that are responsible for causing increased sympathetic activity in high blood pressure, and also in response to acute stress. There is also evidence from studies in humans that drugs which act on a particular type of receptor in the brain (called a serotonin receptor) can strongly inhibit the normal response to stress. We also aim to determine exactly where and how such drugs work. These studies may lead to much more effective treatments for high blood pressure and stress-related disorders.Read moreRead less