When a region of heart muscle is deprived of blood (is ischemic), the oxygen-starved cells begin to metabolize anaerobically, producing lactic acid. The rising H+ level that results hinders the cardiac cells’ ability to produce the ATP they need to pump Ca2+ into the extracellular fluid. The resulting increase in intracellular H+ and Ca2+ levels causes the gap junctions (which are usually open) to close, electrically isolating the damaged cells and forcing generated action potentials to find alternate routes to the cardiac cells beyond them. If the ischemic area is large, the pumping activity of the heart as a whole may be severely impaired, leading to a heart attack
Posted on: Fri, 26 Jul 2013 18:03:03 +0000
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