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Myocytes = muscle cells – cardiomyocytes are cardiac muscle cells.
The Extracellular Matrix or Matrix = the proteins that lie between the muscle cells - the matrix provides tissue rigidity and holds the heart (and all other organs) together. This is where fibroblasts are found.
Fibroblasts = cells which are responsible for healing wounds and contributing to the cardiac matrix (they become hypersynthetic myofibroblasts when activated). When activated (by calcium) they become stimulated to release collagen to create scar tissue. Fibroblasts are found throughout the body, but the heart is unique in the way these proteins continue to work even after their job is done. In other parts of the body they die after a scar has formed, in the heart, they continue to release collagen, eventually leading to a condition called Fibrosis.
Collagen = a major component of the matrix, like a molecular cement, holds muscle cells together. Release is controlled by Fibroblasts. Too much, and the heart can’t function properly.
Fibrosis = A condition which occurs following heart trauma (heart attack) or in the progression of heart disease. Trauma or disease activates Fibroblasts which pump out excessive amounts of collagen creating excess cardiac scarring. Eventually, there is too much scar tissue and the heart can no longer relax or contract properly, causing death. This is why some people may survive a heart attack and then suffer from compensated heart failure later in life.
Calcium = (Ca) an element which provides a very important and common cellular signal. Sustained elevation of Ca inside the cell eg, [Ca 2+]i , via increased Ca influx is important in the regulation of a number of cellular functions, including that of gene expression (collagens), or differentiation of cells. Thus Ca entry to the cell may control cell contraction or secretion of matrix.
NXC1 = The sodium-calcium exchanger. NCX1 is a protein abundant in different cardiac cells (including both myocytes and fibroblasts) which contributes to the movement of calcium. Dr. Hryshko is investigating NCX1 in myocytes, and Dixon is doing so in cardiac fibroblasts. A relatively new area of heart research is the exploration of new drugs that block the function of NCX1. Two types of these drugs include SEA 0400 and KBR7943. Dr. Dixon is examining the use of these drugs to inhibit the NCX1 in fibroblasts, and thereby inhibit fibroblast-based release of collagen.
Statistics
From the Heart and Stroke Foundation
- Over one third (36%) of all deaths in Canada (1999) are due to heart disease and stroke
- 80.2% of Canadians (20-59 yrs) have at least one of the following risk factors for heart disease or stroke: daily smoking, physical inactivity, being overweight, self-reported high blood pressure or self-reported diabetes
- 37% of all female deaths and 35% of all male deaths result from heart disease and stroke
- While more men than women die from coronary artery disease and heart attack, more women than men die from congestive heart failure
- Heart disease and stroke combined are the leading cause of hospitalization for women (excluding childbirth and pregnancy)
- By the age of 70, 1 in 5 women and 1 in 4 men reported having been told by a physician that they had heart problems
- 50% of Canadians with heart problems or stroke required help with daily activities, while only 11.5% of individuals without heart problems or stroke required such help
- Heart disease and stroke combined are the number one cause of hospitalization among men and women in Canada
- The total cost of heart disease and stroke to the Canadian economy is approximately $18.5 billion – more than any other disease
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