Reversible injury in myocardium occurs at ?
Ans. is 'b' i.e., 30 minuteso The metabolic rate of the hea is high, and its stores of substrate are low.o So, hea is critically dependent on a continuous supply of oxygen and nutrients.o Ischemia of myocardium induces profound functional, biochemical and morphological consequences.o Myocardial function is more sensitive to ischemia (loss of contractility occurs within 60 seconds) than myocardialstructure (irreversible injury occurs in 20-40 minutes, thus myocardial necrosis begins at approximately 30 minutesafter coronary occlusion.Key events in ischemic cardiac myocytes Feature TimeOnset of ATP depletion SecondsLoss of contractility < 2 minutesATP reduced to 50% 10 minutesATP reduced to 10% 40 minutesIrrversible injury 20-40 minMicrovascular injury > 1 hr
2 minutes
30 minutes
2 hours
5 hours