Myocardial amino acid metabolism in patients with chronic ischemic heart disease

Abstract

In nine patients with ischemic heart disease the authors investigated the arterio-coronary venous difference of free amino acids in serum at rest and during pacing. At rest aspartate was the only amino acid with a marked positive arterio-coronary venous difference. At the peak of pacing, in addition to aspartate, there is a significant positive arterio-coronary venous difference in glutamate, leucine and isoleucine and a significantly negative difference in cystine-cysteine and glutamine with asparagine. When expressed in per cent of the arterial level, the negative difference in alanine is also significant. Among the mutual correlations of arterio-coronary venous differences the negative correlation between alanine and lactate is most significant, which suggests that under normal conditions pyruvate is transformed rather to alanine, while in ischemia lactate is formed from pyruvate, and released from the heart muscle. There is also a positive correlation between alanine and glutamine and between leucine, isoleucine and glutamate.On the other hand, cystine-cysteine correlates very significantly but inversely with leucine, isoleucine and glutamate.The arterio-coronary venous difference of aspartate, though significantly positive, does not correlate with any other amino acid. The arterio-coronary venous differences of ammonia and uric acid correlate inversely, whereby uric acid, contrary to ammonia, is practically not released from the heart muscle.The importance of amino acids in the energy metabolism of the myocardium is not decisive from the quantitative aspect, various findings suggest, however, that amino acids play an important role in metabolic regulation and under certain conditions may become an essential substrate (8). Amino acids are linked at various sites with metabolic pathways, whereby a decisive role is played by transamination and oxidative deaminations. According to some findings it is probable that in the myocardium, similarly as in skeletal muscle, alanine is produced (9,15,24). The uptake of glutamate and release of alanine is probably associated with the necessity to

Comparative Effects of Aspartate and Glutamate during Myocardial Ischemia

“…It is possible that, relative to the concen tration of amino acids in the perfusate (4 mM), the intracellular concentration of Asp became critically low during ischemia and was supplemented by the exogenously added Asp. In this regard, Brodan et al [1] observed that Asp was the only amino acid which the myocardium extracted to a signifi cantly greater extent during pacing-induced angina in patients with coronary heart dis ease. Also, Kao et al [5] reported that, in the isolated perfused rat heart, anoxia and isch emia caused approximately 75 and 35% de clines, respectively, in intracellular Asp con centrations, whereas no changes in Glu con centrations occurred.…”

Regulation of myocardial amino acid balance in the conscious dog.

“…However, with regard to glutamine, the use in the current study of a recently validated method for glutamine analysis (30) may contribute to the difference of results. It is worth noting that although the chromatographic procedure used in their study limited the resolution of glutamine, Brodan et al (11) reported that a combination of glutamine and asparagine was released by the ischemic human heart. These same authors observed uptake of leucine and isoleucine by human myocardium during pacing stress.…”

The Role of Amino Acids in the Modulation of Cardiac Metabolism During Ischemia and Heart Failure

“…Brodan et al markedly observed a positive myocardial uptake of only aspartate at rest, an uptake of glutamate, leucine, and isoleucine, and the release of cystine-cysteine, glutamine, and asparagine during pacing in 9 patients with ischemic heart disease [30].…”