ated to the length of time before these stores become too low to maintain the required energy production needs of the organ. It is also possible that the tissue stores of ATP and phosphocreatine are critical factors. It is known that the amount of ATP in heart muscle tissues is sufficient to sustain contractile activity of the muscle for less than one second. This is why phosphocreatine is so important. Vertebrate muscle tissue contains a reservoir of high-potential phosphoryl groups in the form of phosphocreatine. Phosphocreatine can transfer its phosphoryl group to ATP according to the following reversible reaction:phosphocreatine + ADP + H+ 9 ATP + creatinePhosphocreatine is able to maintain a high concentration of ATP during periods of muscular contraction. Therefore, if no other energy producing processes are available for the excised heart, it will only remain viable until its phosphocreatine stores run out.A major obstacle that must be overcome in order for heart transplants to be successful, is the typically prolonged delay involved in getting the organ from donor to recipient. The biochemical composition of the preservation media for hearts during the transplant and transportation delays are extremely important for prolonging the viability of the organ. It has been discovered that adding pyruvate, or pyruvate containing compounds like APE-LM, to a preservation medium greatly improves post-preservation cardiac function of the heart. As was discussed, the pyruvate is able to enter the citric acid cycle and produce sufficient amounts of energy to sustain the heart after it has been excised until it is transplanted.Increasing the amount of time a heart can remain alive outside of the body prior to transplantation from the current four hours to 24 hours has many desirable benefits. As discussed earlier, this increase in time would allow doctors the ability to better match the tissues of the donor with those of the recipient. Organ r...
