ADA and ischemia: The group’s work (Schulz et al., 1995), published in 1994, compared four groups: a first group subjected to 90 min of ischemia, a second group subjected to an initial 10-minute period of ischemia (i.e., ischemic pre-conditioning) followed by a 15-minute period of reperfusion prior to a 90-minute period of ischemia, a third group receiving intra-coronary infusion of adenosine deaminase maintained throughout the 90-minute ischemic period, and a final group undergoing ischemic pre-conditioning with concomitant adenosine deaminase infusion and subsequent 90-minute ischemia.