MYOCARDIAL RELEASE OF INOSINE, HYPOXANTHINE AND LACTATE DURING PACING-INDUCED ANGINA IN HUMANS WITH CORONARY-ARTERY DISEASE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 9  (3) , 227-240
Abstract
The applicability of ATP catabolites, inosine and hypoxanthine as markers of myocardial ischemia in humans with coronary artery disease was investigated. Inosine and hypoxanthine were assayed enzymatically after separation by column chromatography. Myocardial lactate extraction at rest (17 .+-. 13%) changed to production values (-23 .+-. 28%) during pacing-induced angina (P < 0.0005). Coronary venous inosine values increased from 535 .+-. 185 nmol/l at rest to 1030 .+-. 740 nmol/l during angina (P 0.005), the arterial values amounted to 770 .+-. 325 nmol/l and 805 .+-. 515 nmol/l, respectively, (P, NS [not significant]). The calculated myocardial uptake of inosine at rest (27 .+-. 16%) changed to production values (-25 .+-. 29%) during angina (P < 0.0005). Coronary venous hypoxanthine increased from 1000 .+-. 760 nmol/l at rest to 1235 .+-. 800 nmol/l during angina (P, NS) and the arterial values to 1300 .+-. 1040 nmol/l and 1235 .+-. 800 nmol/l, respectively (P, NS). Myocardial extraction changed from 20 .+-. 18% at rest to -5.4 .+-. 29% during angina (P 0.0025). The significant positive correlation (r [correlation coefficient] = 0.61, P < 0.0025) between myocardial release and uptake of inosine and lactate during severe angina demostrates that anerobic glycolysis accompanies ATP breakdown. During a 2nd pacing period at less increased pressure-rate product after nitroglycerin, lactate production (-1.7 .+-. 22%) already occurred and extraction of inosine (19 .+-. 19%) and hypoxanthine (24 .+-. 15%) did not change. Lactate functions as a sensitive marker of myocardial ischemia and inosine is useful in detecting ischemic myocardial energy deficiency by indication of insufficient glycolytic ATP supply.