The effect of cyanide on isolated perfused rat heart

Using Langendorff isolated perfused rat hearts, we demonstrated direct effects of cyanide on the heart. A heart from a sacrificed male rat was placed on a Langendorff apparatus and perfused with Tyrode solution containing 2.0 mM NaCN (CN-TS), following with normal Tyrode solution (TS) at 37 degrees C. During perfusion we monitored the heart beat, and the state of inorganic phosphate (Pi), creatine phosphate (CrP) and adenosine triphosphate (ATP) by 31P-NMR spectrometer equipped with a surface coil probe. After the beginning of the CN-TS perfusion, the heart was initially excited, and ceased beating completely seventy seconds later. During CN-TS perfusion, the CrP immediately disappeared, but the ATP level was maintained considerably. The peak of Pi shifted to the right, indicating acidosis in the heart. These results suggest that the ATP level in a heart during exposure of cyanide is maintained by activation of anaerobic glycolysis in compensation for cellular oxygen utilization.