Effect of ischemia and 24 hour reperfusion on ATP synthesis in the rat kidney

The ability of renal tissue to synthesize ATP was examined in adult Sprague Dawley Rats immediately following normothermic ischemia of 30, 45, 60 and 90 minutes and upon reperfusion for 24 hours. Following ischemia the rate of ATP synthesis decreased progressively. It was 64.5% of the control at 45 minutes and 10.4% after 90 minutes of ischemia. Reperfusion of the ischemic kidneys for 24 hours restored ATP biosynthesis to control, nonischemic levels in kidneys subjected to ischemia up to 45 minutes (101.8 +/- 13.9% vs 64.5 +/- 2.5% p less than 0.02). However, after 60 minutes of ischemia, reperfusion had no effect (59.3 +/- 4.4% vs 51.7 +/- 7.5%) and reperfusion following 90 minutes of ischemia was associated with decrease ATP synthesis (10.4 +/- 2.2% vs 3.3 +/- 0.9% p less than .001). We conclude that mitochondrial function is restored by reperfusion when normothermic ischemic interval is 45 minutes or less. However, ischemic intervals longer than 45 minutes produce non-reversible impairment of ATP synthesis and the marked reduction following 90 minutes of ischemia signifies possible transition to a non-viable state.