Aminosulfonic acid buffer preserves myocardium during prolonged ischemia

Acid-base buffering in organ preservation solutions as a function of temperature: new parameters for comparing buffer capacity and efficiency

Control of acidity and preventing intracellular acidosis are recognized as critical properties of an effective organ preservation solution. Buffer capacity and efficiency are therefore important for comparing the relative merits of preservation fluids for optimum hypothermic storage, but these parameters are not available for the variety of organ preservation solutions of interest in transplantation today. Moreover, buffer capacity is dependent upon both concentration and pH such that buffer capacity is not easily predicted for a complex solution containing multiple buffer species. Using standard electrometric methods to measure acid dissociation constants, this study was undertaken to determine the maximum and relative buffer capacities of a variety of new and commonly used hypothermic preservation solutions as a function of temperature. The reference data provided by these measurements show that comparative buffer capacity and efficiency vary widely between the commonly used solutions. Moreover, the fluids containing zwitterionic sulfonic acid buffers such as Hepes possess superior buffering for alpha-stat pH regulation in the region of physiological importance.

Beneficial effect of HEPES buffer in repeated coronary reperfusion

BACKGROUND

We 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.

OBJECTIVE

To study the effect of HEPES buffer on infarct size, using a repeated-reperfusion model.

METHODS

The 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.

RESULTS

Hemodynamic 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 < 0.001).

CONCLUSION

Treatment with HEPES induces a beneficial effect by reduction of infarct size in repeated coronary reperfusion.