lucose substrate did not transport or consume that substrate, even when it was provided as the sole exogenous substrate. It might be expected that glucose would be used up in a manner similar to that of pyruvate. This expectation is because glucose is a precursor to pyruvate via the glycolytic pathway however, this was not the case. It was theorized this lack of glucose use may have been due to the fact that the hormone insulin was not present in the media. Without insulin, one may think the tissues of the heart would be unable to adequately take glucose into their tissues in any measurable amount, but this is not the case either. It is known that hearts working under physiologic conditions do use glucose in the absence of insulin, but glucose consumption in that situation is directly related to the performance of work by the heart, not the presence of insulin. To further test the effects of the addition of insulin to the glucose media, experiments were done in which the hormone was included in the heart preservation media5-7. Data from those studies does not provide evidence that the hormone is essential to insure glucose use or to maintain the metabolic status of the heart or to improve cardiac recovery. In a hypothermic (80C) setting, insulin did not exert a noticeable benefit to metabolism beyond that provided by oxygen and glucose. This hypothermic setting is analogous to the setting an actual heart would be in during transportation before transplant. Another study was done to determine whether the compound perfluoroperhydrophenanthrene-egg yolk phospholipid, (APE-LM) was an effective media for long-term hypothermic heart preservation3. Two main factors make APE-LM an effective preservation media. (1) It contains a lipid emulsifier which enables it to solubilize lipids. From this breakdown of lipids, ATP can be produced. (2) APE-LM contains large amounts of pyruvate. As discussed earlier, an abundance of energy is produced via the ...
