Beneficial effect of HEPES buffer in repeated coronary reperfusion

BACKGROUNDWe have demonstrated previously that, when repeated reperfusion is performed after reocclusion, there is a decrease in the amount of myocardial salvage, despite early reperfusion. Treatment with nisoldipine induced a beneficial effect by reduction of infarct size in this experimental model. OBJECTIVETo study the effect of HEPES buffer on infarct size, using a repeated-reperfusion model. METHODSThe left anterior descending coronary artery was occluded in anesthetized dogs. Thirty minutes after the occlusion, dogs were allocated randomly to either the treatment group (n = 7; HEPES 0.64 mmol/l infused intravenously throughout the experiment) or the control group (n = 8; saline). Occlusion was maintained for 2 h, followed by 1 h of reperfusion, then 1 h of reocclusion and 2 h of second reperfusion. An in-vivo area at risk was determined by gentian violet staining, and infarct size was defined and quantitated by triphenyl-tetrazolium chloride staining. RESULTSHemodynamic measurements were similar in both groups. Mass of necrosis/mass at risk was significantly smaller in the HEPES group (30.7 ± 1.6%, mean ± SEM) compared with controls (50.6 ± 3.8%, P