During ischaemia, the glycolytic pathway (Embden-Meyerhof) is up regulated in an attempt to produce ATP anaerobically. However, this is short-lived due to negative feedback on the key glycolytic enzyme phosphofructokinase by accumulating lactate. Fructose-1,6-diphosphate (FDP), a high energy intermediary metabolite of this pathway, is unique in that is enters glycolysis distal to this inhibitory site. Exogenously administered FDP should therefore theoretically yield ATP independent of lactate accumulation and thereby ameliorate ischaemic injury. Clinical benefit has been shown in coronary artery bypass grafting (CABG) surgery, congestive cardiac failure and adult respiratory distress syndrome. Ischaemia-reperfusion injury induced by cardiopulmonary bypass (CPB) presents clinically as an impairment of myocardial function in the postoperative period. At a cellular level this reflects myocardial metabolic changes and nucleotide degradation (directly linked to high energy phosphate turnover). Quantification of myocardial nucleotide catabolite release therefore provides useful information regarding intermediary metabolism and cytoprotection conferred to myocardial (inosine, uridine) and endothelial (hypoxanthine) tissue. The authors investigated the myocardial cytoprotective effects of FDP in 16 patients scheduled for elective CABG surgery. Aortic and coronary sinus blood were collected directly into liquid nitrogen and analysed by high performance liquid chromatography prior to CPB and at different time points after reperfusion. FDP was administered intravenously in 8 patients and 5% dextrose was administered in 8 other patients. Analysis of transmyocardial (coronary sinus-aortic) nucleotide metabolite levels showed increased release of inosine, hypoxanthine and uridine in both the FDP and the control groups following reperfusion. However, compared to baseline (pre-aortic clamping) values, hypoxanthine and inosine concentrations were significantly elevated at 0, 1, 5 and 10 minutes following reperfusion in the control group. This was in contrast to earlier recovery to baseline levels (after 5 minutes of reperfusion) in the FDP group. Furthermore, when compared to control group, the hypoxanthine and inosine concentrations were significantly decreased by FDP treatment. Uridine concentrations were significantly elevated at 1 and 5 minutes in the control group and no significant change was observed in the FDP group. In conclusion, these data suggest that FDP, through an intermediary metabolic effect, may contribute to myocardial and endothelial cytoprotection during the ischaemic insult of cardiac surgery.
|Translated title of the contribution||Effect of fructose-1,6-diphosphate on myocardial purin and pyrimidin metabolism during coronary artery bypass grafting surgery|
|Number of pages||5|
|Publication status||Published - Sep 10 2000|
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