CARRIER-MEDIATED TRANSPORT CONTROLS HYDROXYPROLINE CATABOLISM IN HEART-MITOCHONDRIA FROM SPONTANEOUSLY HYPERTENSIVE RAT

In this study we have investigated hydroxyproline transport in rat hea rt mitochondria and, in particular, in heart left ventricle mitochondr ia isolated from both spontaneously hypertensive and Wistar-Kyoto rats , Hydroxyproline uptake by mitochondria, where its catabolism takes pl ace, occurs via a carrier-mediated process as demonstrated by the occu rrence of both saturation kinetics and the inhibition shown by phenyls uccinate and the thiol reagent mersalyl, In. any case, hydroxyproline transport,vas found to limit the rate of mitochondrial hydroxyproline catabolism, A significant change in V-max and K-m values was found in mitochondria from hypertensive/hypertrophied rats in which the K-m val ue decreases and the V-max value increases with respect to normotensiv e rats, thus accounting for the increase of hydroxyproline metabolism due to its increased concentration in a hypertrophic/hypertensive stat e.