Myofilament Calcium Responsiveness in Stunning and Preconditioning

PÉREZ NG; TAKEDA N ; SINGH M

Myocardial Ischemia and Preconditioning

Kluwer Academic Publishers

Lugar: Boston; Año: 2003; p. 283 - 292

When the heart is subjected to a brief but severe episode of ischemia, a prolonged contractile dysfunction becomes evident upon reperfusion, despite the absence of irreversible tissue damage. This acute and fully reversible form of pump failure has been called ?myocardial stunning? and is characterized by a decreased myofilament Ca2+ responsiveness, because of a selective Ca2+-activated troponin I proteolysis during the early reperfusion. Interestingly, when the heart is pretreated with one or more short cycles of ischemia-reperfusion, a paradoxical protection against a subsequent ischemic episode takes place. This protective effect is known as ischemic preconditioning and is characterized by the preservation of the myofilament responsiveness to Ca2+.