A study on the function of some subcellular systems of the sheep myocardium during gousiekte. I. The energy production system.

In order to determine the status of the energy production system of the heart during cardiac failure of sheep with gousiekte, observations were made of the heart tissue levels of adenosine triphosphate (ATP), creatine phosphate (CrP), inorganic phosphate, reduced nicotine adenine dinucleotide (NADH) and lactate. Some measurements on oxidative phosphorylation were also made. A significant decrease in ATP and CrP levels coincided with a simultaneous rise in the ATP:CrP ratio and lactate levels in gousiekte hearts. No significant deviations in inorganic phosphate and NADH levels could be demonstrated. These abnormalities were accompanied by a decreased uptake of oxygen by isolated mitochondria of gousiekte hearts. There was a marked increase in the anaerobic state of the hearts of dying gousiekte sheep, while the values of NADH and the ATP:CrP ratio at a presymptomatic stage indicated a possible early derangement in the energy metabolism of sheep fed the toxic material. No hypertrophy could be detected for the failing ventricles of gousiekte sheep after being corrected for a significant amount of oedema found in the heart tissue of these animals. It was concluded that the depressed ATP and CrP levels in the heart tissue of gousiekte sheep during cardiac failure could at least in part, be attributed to a depressed aerobic energy production. It is not possible, however, to state whether this is a primary or a secondary response due to intoxication and also whether it could be seen as a cause or effect of cardiac failure.