The Metabolism of Contraction (dedikált példány) [antikvár]

Recent Advances in Studies on Cardiac Structure and Metabolism Volume 10 The Metaholhm of Contraction Ivdited by Paul-Kmile Roy and George Rona O 1975 University Park Press Haltimore ASSESSMENT OF MYOCARDIAL FREE FATTY ACID METABOLISM IN HUMANS DURING HEPARIN INFUSION GILLI-S R. DAGENAIS, YVES MARQUIS, and LAIMONIS GAILIS Inslitut de Cardiologie de Qudbec, Qudbec, Canada SUMMARY I-'rce fatly acids (l-'FA) have been shown to be the major myocardial substrates during the postabsorptive state in humans. In order to document the utilization of these substrates by Ihe heart while heparin was infused, the following study was designed. During heparin infusion, total and individual I TA were measured in arterial and coronary sinus plasma during (he postabsorptive state in I 3 patients with coronary artery disease and in 4 patients Willi no evidence of cardiac disease. 01eic-l-'''C acid bound to albumin was infused at a constant rale for at least 7 niin into tlie lefl coronary artery. Left coronary blood flow was determined in all patients. II was assumed that olcic-l-''^C acid behaves like endogenous M'A. Arterial I'l'A concentration was high (mean and SEM: 1.52 ± 0.21 Mmoles/ml) and varied by less than 10% during the course of the study in 14 of the 17 patients. Oleic acid constituted 44% of all arterial FFA. The relative concentrations of the various individual I'l'A were similar in arterial and coronary sinus plasma. The average FFA extraction was 19.9 I 2.1%. In contrast, the oleic-l-''^C acid extraction was relatively more steady during Ihe infusion, and the mean extraction of this tracer was 36.0 ± 2.1%. Myocardial uptake for the entire group was 52.3 ± 6.3 /i"H)les/min. Although a definite plateau for '"COj release from oleic-! - '"'C acid oxidation was not obtained, al least 31.8 ± 4.3% of the removed FFA was oxidized, representing 49.3 ± 6.4% of myocardial oxygen consumption. The failure of oleic-l-'''C acid oxidation to reach a steady state was not due to delay in the myocardial COj pool, since '"COj release from infused Nail'"CO, and lactate-l-'"C in 11 other subjects revealed thai an equilibrium was obtained within 5 min. These findings indicate that the generation of '"COj from oleic-)-'"C acid oxidation is relatively slow, and tlie uptake of labeled I'FA is partly matched by release of unlabeled FFA, suggesting that the human heart has important lipid pools. INTRODUCTION Free fiitty acids (FFA) constitute the major metabolic substrates of the human heart during the postabsorptive slate. To date, no study has assessed how the human myocardium utilizes these substrates when their plasma concentrations are elevated. Increased arterial FFA are often encountered in clinical situations such as shock and heparin or catecliolamine infusion and, according to some reports, may have deleterious effects on the ischemic myocardium (Oliver,