ATP SYNTHESIS AND EXPORT IN HEART LEFT-VENTRICLE MITOCHONDRIA FROM SPONTANEOUSLY HYPERTENSIVE RAT

Use was made of mitochondria isolated from heart left ventricles of ei ther spontaneously hypertensive or age-matched Wistar-Kyoto rats used as a control to find out whether hypertrophy (5-week-old rats) or hype rtrophy/hypertension (24-week-old rats) can cause change in the mechan isms by which ATP is synthesised via ATP synthase and subsequently exp orted via the ADP/ATP translocator outside mitochondria. To do this, p hotometric measurements were made of the rate of ATP appearance in the extramitochondrial phase, which occurs as a result of ADP addition to mitochondria. In mitochondria from spontaneously hypertensive rats de ficit of ATP production was found dependent on changes in the Km(ADP) and V-max values of both the ADP/ATP translocator and the ATP synthase . The ADP/ATP translocator was found to determine the rate of ATP prod uction outside mitochondria in all the tested samples. In an initial i nvestigation carried out to ascertain how cell ATP deficit can be coun terbalanced, an increase in both adenylate kinase and creatine kinase activities was found in both hypertrophy and hypertrophy/hypertension. A possible increase in anaerobic glycolysis was also suggested by the increased lactate dehydrogenase activity.