Adenine nucleotide degradation in the human myocardium during cardioplegia

The tissue content of adenine nucleotides and their metabolites, inosine monophosphate, adenosine, hypoxanthine, and uric acid, were determined in biopsy specimens from the left ventricle of six patients during cardioplegia for open heart surgery. Biopsy specimens were collected immediately after the induction and at the end of cardioplegia (51-82 min) and were analysed by high performance liquid chromatography. After the induction of cardioplegia (cold potassium enriched solution) the left coronary artery was continuously perfused with cold (10 degrees C), potassium enriched, diluted blood. The adenosine triphosphate concentration decreased from 13 to 8 mmol.kg-1 dry muscle (p less than 0.01) during cardioplegia. Adenosine diphosphate and adenosine monophosphate concentrations were 6 and 3 mmol.kg-1 dry muscle respectively and remained unaffected. The adenosine concentration (0.3 mmol.kg-1 dry muscle) was three times higher than that of inosine monophosphate. Inosine concentrations increased from 0.8 to 2.7 mmol.kg-1 dry muscle (p less than 0.01) in parallel with the increase in hypoxanthine from 0.1 to 0.4 mmol.kg-1 dry muscle (p less than 0.01). The total adenine nucleotide pool decreased by 5 mmol.kg-1 dry muscle (p less than 0.01), whereas the corresponding increase in nucleotides and bases only was 2 mmol.kg-1 dry muscle. In conclusion, the adenosine triphosphate content and the adenine nucleotide pool were appreciably reduced during continuous cold blood cardioplegia as used in the present study. The tissue content of adenosine and further metabolites was considerably increased.(ABSTRACT TRUNCATED AT 250 WORDS)