Increase of coronary flow by anoxia, iodoacetic acid, and 2,4-dinitrophenol in isolated rat hearts

Abstract

Hat hearts were perfused with the Langendorff’s technique. Perfusate containing glucose oxygenated with 95% O2 + 5% CO2 was used for most of the experiments. Anoxia was induced by perfusion with the same perfusate except that it was bubbled with 95% N2 + 5% CO2. The effect of anoxia, iodoacetic acid (IAA), and 2,4-dinitrophenol(DNP) on the oxygenation level of tissue myoglobin(Mb.O2), oxidation level of tissue cytochrome aa3(Cyt. aa3), heart rate(HR), coronary flow (CF), left ventricular pressure(LVP), and the tissue levels of ATP, creatine phosphate(CrP), and lactate were investigated. The Mb.O2 and Cyt.aa3 were measured by the optical method. Anoxia decreased Mb.O2, Cyt.aa3, HR, and LVP, and increased CP. The levels of ATP and CrP decreased and the levels of lactate increased after anoxia. IAA(0.1mg/min) increased CP without affecting Mb.O2, Cyt.aa3, HR, and LVP. The levels of ATP and CrP were reduced by IAA. DNP(50pg/min) decreased Mb.02, Cyt.aa3, and LVP, and increased CF without affecting HR. The levels of ATP and CrP were reduced by DNP. It is suggested that the anoxia-, IAA-, or DNP-induced increase in CF is closely related to loss of ATP and CrP in the heart muscle and that IAA increases CF even when the intracellular oxygen level does not decrease.