Dynamics of myocardial metabolism in the preconditioned porcine heart studied using continuous microdialysis

Abstract

A microdialysis technique was used to measure myocardial catabolism of adenine nucleotides during preconditioning. Following thoracotomy in domestic pigs, a probe was inserted into the ischaemic myocardium and two probes into normal myocardium. Preconditioning was instituted by occluding a diagonal branch of the left anterior descending coronary artery four times over a 10 min period (interspersed with 20 min of reperfusion each time), followed by index ischaemia for 40 min and terminated by 20 min of reperfusion. Non-preconditioned animals, which had been subjected to 40 min ischaemia and 20 min of reperfusion were used as controls. Sham operated animals were additional controls. Following equilibration, the dialysis fluid was continuously pumped and the microdialysate analysed at 5 min intervals. In the dialysate, the amount of lactate, pyruvate, adenosine, inosine, hypoxanthine and guanosine was measured. Circulatory parameters were: rate pressure product, pulmonary artery pressures, cardiac output and pulmonary wedge pressure. There was no significant statistical difference in cardiac work between preconditioned pigs and controls. A sharp rise in adenosine was observed during the first short ischaemic period with attenuation during the following three short ischaemic periods. In the microdialysate, lactate, adenosine, inosine, hypoxanthine and guanosine were significantly lower during index ischaemia in the preconditioned group than in the non-preconditioned group. Pyruvate levels decreased during preconditioning and rose to a higher level after each brief ischaemic period, followed by a decrease, which was proportionally similar in the preconditioned and unpreconditioned animals during index ischaemia. The effect of preconditioning on lactate and catabolite levels indicated a powerful inhibition of adenine nucleotide catabolic processes due to ischaemia.

Coronary microembolization does not induce acute preconditioning against infarction in pigs?the role of adenosine

“…With coronary microembolization, the interstitial adenosine increased only after the onset of the sustained ischemia and this increase during the sustained ischemia was attenuated. An attenuation of increases in the interstitial adenosine concentrations during the prolonged ischemia after ischemic preconditioning was reported for rabbits [16,17], pigs [18] and dogs [19] and was also observed in the present study. However, this attenuation of an increase of the interstitial adenosine concentration appears to be unrelated to a protective effect.…”

Polyol-pathway-dependent disturbances in renal medullary metabolism in experimental insulin-deficient diabetes mellitus in rats

“…Concentrations of lactate, pyruvate, adenosine, inosine and hypoxanthine were analysed using an HPLC technique with UV detection [15,16]. Glucose concentrations were measured with CMA/600 (CMA/Microdialysis), which uses enzymatic reagents and absorbance measurements at 546 nm.…”

Functional Recovery of Chronic Ischemic Myocardium after Surgical Revascularization Correlates with Magnitude of Oxidative Metabolism

“…In general, we found a faster recovery and a better oxidative energy metabolism in the segments with improved wall motion, comparable to data we collected from the normokinetic right ventricular control group. Glucose assumes a central role for the energy production in the ischemic heart, when a lack of oxygen induces a shift to anaerobic metabolism with rapid stimulation of glucose uptake, glycogenolysis and glycolytic flux [27]. Interstitial glucose levels appear to depend on myocardial blood flow and glucose delivery to the tissue.…”