Approximate time, at the end of which the quantity of ATP within ischemic cardiac myocytes is reduced to 10% of the original is: (A) <2 minutes, (B) 10 minutes, (C) 20 minutes, (D) 40 minutes
Answer is D. Metabolic changes slow as the duration of ischemia increases. Irreversibly injured myocytes exhibit (a) very low levels of ATP (less than 10% of control); (b) cessation of anaerobic glycolysis; (c) high levels of H+, AMP, INO, lactate, and alpha GP; (d) a greatly increased osmolar load; (e) mitochondrial swelling and formation of amorphous matrix densities; and (f) disruption of the sarcolemma. Approximately 40 minutes of time may there as the metabolic changes slow down with the decrease in ATP levels Ref internet and Robbins 9/e p,27;28