Embryonic versus adult myocardium: adenine nucleotide degradation during ischemia

The Effects of Pentoxifylline on the Myocardial Inflammation and Ischemia-Reperfusion Injury During Cardiopulmonary Bypass

BACKGROUND

Pentoxifylline (Ptx) decreases necessity of cell energy and inflammatory reactions via inhibition of 5'-nucleotidase (5'-NT). The aim of this study is to investigate whether the addition of Ptx into the cardioplegic solutions avoids myocardial inflammatory reactions and ischemia/reperfusion (I/R) injury during extracorpereal circulation.

METHODS

Between December 1999 and February 2002, we operated 75 patients with the diagnoses of atrial septal defect (ASD), ventricular septal defect (VSD), valve disease, and coronary disease. The average age of patients was 42.4 and male-female ratio was 1: 1.5. The patients were divided into two groups, which were the study group (n = 40) and the control group (n = 35). We used cold blood cardioplegia mixed with St. Thomas' Hospital II cardioplegic solution for both of the groups. Ptx was added into the cardioplegic solution (500 mg/L) in the study group. Interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrotisis factor-alpha (TNF-alpha) levels in coronary sinus blood samples during cross-clamp time (X-clamp) and after releasing of it and tissue TNF-alpha in the right atrial appendix biopsy material that was taken after X-clamp were studied to compare the both groups.

RESULTS

After releasing X-clamp, results of blood TNF-alpha, IL-6, and IL-8 of both groups were statistically significant (p < 0.005). At the pathological examination, we also observed that the amount of tissue TNF-alpha in the control group (66 +/- 17.1) was much higher than the study group (16.6 +/- 5.9, p <0.005).

CONCLUSIONS

These results show that Ptx may be added into cardioplegic solution to avoid the myocardial inflammation and I/R injury during open heart surgery.

Major abdominal surgery of the neonate: anaesthetic considerations

The anaesthetic handling of neonates scheduled for major abdominal surgical procedures is one of the most demanding tasks that can confront an anaesthesiologist. This chapter will review the specific physiological characteristics of the newborn with relevance to anaesthesia and will also provide robust guidelines for the anaesthetic handling of the most frequent diagnoses that need major abdominal surgery during the neonatal period.

Regulation of cardiac AMP-specific 5'-nucleotidase during ischemia mediates ATP resynthesis on reflow

The ability to resynthesize ATP during recovery from ischemia is limited to the size of endogenous pool of adenine nucleotides. Cytosolic AMP-specific 5'-nucleotidase (5'-NT) plays a key role in ATP degradation and hence the capacity for ATP resynthesis. We have suggested (J. Clin. Invest. 93: 40-49, 1994) that intracellular acidosis [intracellular pH (pHi)] is a potent inhibitor of 5'-NT under in vivo conditions. To test this hypothesis further, we used the hyperthyroid rat heart because we could alter pHi during ischemia and determine the consequences of lower pHi on AMP accumulation (by chemical assay) and ATP resynthesis (by 31P nuclear magnetic resonance spectroscopy) during reperfusion. Global no-flow ischemia caused pHi to decrease from 7.1 under well-oxygenated control perfusion to 6.7. We found that decreasing pHi further from pH 6.7 to 6.4 leads to increased accumulation (30%) of AMP during ischemia and to a 2.5-fold increase in ATP resynthesis during reperfusion. Analysis of all known substrates, products, activators, and inhibitors of the 5'-NT suggests that 5'-NT is activated primarily by Mg2+ and ADP and is inhibited by H+. Thus these observations provide evidence for a salutary effect of intracellular acidosis on preserving the AMP pool due to inhibition of 5'-NT and suggest a novel role of H+ in protecting ischemic tissue.