Relationship between myocardial adenine nucleotide catabolism and tissue blood flow rate in experimental ischaemia

A method was developed for tissue preservation and evaluation of the adenine nucleotide metabolism in small samples of myocardium after 45 min of ischaemia. Ischaemia was produced by coronary artery occlusion in anaesthetized cats. Adenine nucleotides and their metabolites were measured by isocratic liquid chromatographic systems which allow quantitative analysis of the nucleotides and their metabolites inosine, hypoxanthine and xanthine in biopsies of 5-20 mg tissue. Regional myocardial blood flow was measured in the tissue surrounding the biopsies by the distribution of 15 micron radiolabelled microspheres. In central ischaemic regions the ATP level was approximately 1 mumol/g wet weight, whereas in normally perfused myocardium the ATP level was approximately 5 mumol/g tissue. In tissue with intermediate flow values, intermediate ATP levels were found. Energy charge, which summarizes all adenine nucleotide concentrations, was reduced from 0.88 to 0.50, and the molar concentrations of inosine, hypoxanthine and xanthine increased in ischaemic tissue. We conclude that this method provides reliable characterization of the local cellular energy status in cat hearts with ischaemic regions.