Myocardial metabolism of glutamate and left ventricular function in patients with coronary arterial disease

Fractional myocardial extraction of glutamate, glutamine, ammonia, glucose and lactate was studied in 35 male patients during rest and atrial pacing. Fourteen patients had no coronary arterial disease. In 21 patients with coronary arterial disease and left ventricular dysfunction the increased myocardial extraction of glutamate at rest positively correlated with increased extraction of glucose, lactate and glutamine release, while it was inversely related to ammonia release. In 9 of these 21 patients pacing did not affect either left ventricular contractile function or myocardial metabolism of all studied compounds. In the other 12 patients pacing caused a decrease in left ventricular ejection fraction, velocity of circumferential fiber shortening and new regional wall motion abnormalities. A more pronounced pacing-induced left ventricular dysfunction was accompanied by myocardial lactate production and 2-fold decrease in myocardial glutamate extraction which was associated with the reduction of glutamine release and increased myocardial ammonia production. Possible relationships between alterations in myocardial glutamate metabolism and diminished ventricular performance have been reviewed. The results suggest the importance of myocardial glutamate extraction for the contractile function of human ischemic heart.