An increased sensitivity of the mitochondrial permeability transition pore to calcium in the heart of rats with chronic deficiency of nigrostriatal dopamine

Abstract We studied the sensitivity of mitochondrial permeability transition pore (MPTP) opening to natural inductors--Ca2+ ions in the rat heart mitochondria with chronic deficiency of nigrostriatal dopamine caused by an injection of selective neurotoxin 6-hydroxidofamine in an ascending lateral bundle of the forebrain. MPTP-opening was determined specrophotometrically (lamda=520 nm) by a decrease in an optical density resulting from mitochondrial swelling. It has been shown that the rat heart mitochondria with chronic deficiency of nigrostriatal dopamine are more sensitive to Ca2+ in its physiological concentration (10(-7) mol/l) and overload (10(-6) - 10(-4) mol/l) in comparison to control animals. Thus, obtained results lead to a conclusion that an increased sensitivity of the mitochondrial permeability transition pore to calcium and mitochondrial membrane permeability may be one of the causes previously reported of disturbance in contractile function of the rat heart with chronic deficiency of nigrostriatal dopamine.