Concentration of lysophosphatidyl choline was slightly increased in heart tissue within 30 min after total rabbit myocardial ischemia and it was distinctly decreased within 1 hr as compared with ...control values. In the mitochondria within the initial periods (0.5 hr, 1 hr) of the ischemia concentration of lysophosphatidyl choline increased most markedly but the phospholipid content became similar to control level within 2 hrs. Alterations in the total phospholipid content whereas separate phospholipid fractions, lysophosphatidyl choline and cardiolipin, altered more distinctly in mitochondria. In ischemically impaired cell phospholipases appear to be initially involved in degradation of mitochondria phospholipids.
The oxidation rates of acetate, acetyl carnitine, caprinate, palmitoyl carnitine and palmitoyl CoA were studied in mitochondria of rabbit heart after short-term (60 min) occlusion of coronary artery ...with subsequent reperfusion within 1 day and 6 days. Oxidation of these substances was similarly decreased. Incomplete oxidation of palmitoyl carnitine was characteristic for mitochondria impaired with ischemia. The data obtained suggest that the outer carnitine palmitoyl transferase was the limiting enzyme for the palmitoyl CoA oxidation in control and impaired mitochondria. The rate of palmitoyl carnitine and caprinate oxidation was apparently decreased at the initial steps of oxidation as soon as consumption of acetate in the tricarboxylic acid cycle exceeded distinctly its formation from these substances.
The rate of oxidation of NADH and 3-hydroxybutyrate was studied in heart mitochondria after short-term (60 min) occlusion of coronary artery and the subsequent reperfusion. Addition of NAD increased ...the rate of 3-hydroxybutyrate oxidation, lowered in mitochondria of impaired tissue, but no complete restoration occurred. The 3-hydroxybutyrate dehydrogenase activity was decreased by 25%. The rate of NADH oxidation in ultrasonicated mitochondria from the infarction zone exceeded 2-fold the rate of 3-hydroxybutyrate oxidation. These data suggest that deficiency of NAD limited primarily the rate of 3-hydroxybutyrate oxidation in heart mitochondria under conditions of experimental myocardial infarction. The level of 3-hydroxybutyrate dehydrogenase activity appears to restrict the rate of 3-hydroxybutyrate oxidation after addition of NAD.
Myocardial mitochondria (MCh), isolated with rotenone (MCh + RO) and in absence of rotenone (MCh - RO), were studied in rabbits with ischemia (0.5 hr autolysis) and in controls. Content of acyl-CoA ...was increased by 50%, linoleic acid - by 49% and lysophosphatidyl choline - by 37% in MCh + RO of control animals as compared with the MCh - RO preparation. In the MCh + RO preparation from rabbits with ischemia content of acyl-CoA was increased by 62%, while concentration of free fatty acids (FFA) and phospholipids was similar to those of the MCh - RO preparation. After isolation of mitochondria with rotenone composition of adenine nucleotides was distinctly altered. Content of ATP was decreased by 27% in mitochondria of both ischemic and control animals, although total amount of adenine nucleotides was decreased only slightly. As shown by estimation of succinate oxidation and membrane potential rotenone did not affect the mitochondrial respiration. In mitochondria of ischemic rabbits concentrations of FFA and lysophosphatidyl choline were increased, whereas content of ATP, total amount of adenine nucleotides, the rate of succinate oxidation and membrane potential were decreased. The method developed, isolation of mitochondria with rotenone, may be used in studies of the role of acyl-CoA in energy metabolism of cells.
Content of unesterified fatty acids (FFA), phospholipids and triglycerides was studied in myocardium of control rabbits, of rabbits with ischemia (1 hr and 4 hrs) of myocardium and in postischemic ...reperfusion. In the ischemic myocardium content of phospholipids was gradually decreased; FFA increased within the first hour of ischemia. In reperfusion and prolongation of ischemia up to 4 hrs FFA were not altered. The data obtained suggest that a decrease in the ratio between the rates of FFA consumption and of lipid hydrolysis was responsible for an increase in the FFA content and in the phospholipid concentration.
A simple procedure is developed for estimation of the damage rate of inner membrane of heart mitochondria. In the assay the rate of succinate oxidation was measured using bromthymol blue as an ...inhibitor of succinate transport. Bromthymol blue at low concentration (12 microM) functioned as a mixed type inhibitor of succinate oxidation, whereas at high concentrations--as uncompetitive inhibitor. Polarographic registration of cytochrome c content and of the rate of ascorbate oxidation in the samples containing Triton X-100 and free of the detergent was more sensitive procedure as compared with spectrophotometric measurement of reduced cytochrome c oxidation in estimation of the damage rate of outer mitochondrial membranes. The damage rates of outer and inner membranes of heart mitochondria isolated by a procedure which included the treatment with trypsin were equal to 8.43 +/- 0.74% and 8.04 +/- 1.9%, respectively, while in those isolated without the trypsin treatment--12.8 +/- 1.5% and 13.3 +/- 1.8%, respectively.
Effect of ischemia and cytochrome c on oxidation of pyruvate and malate as well as of 3-hydroxybutyrate, succinate and exogenous NADH was studied. Respiration of mitochondria at the state 3 was ...markedly decreased in presence of the mixtures free of cytochrome c and containing pyruvate and malate, 3-hydroxybutyrate and succinate. In the same mixtures, but containing cytochrome c, oxidation of NAD-dependent substrates was decreased less distinctly and oxidation of succinate was similar to the control values. The rate of rhothenone-sensitive oxidation of NADH as well as the activating effect of cytochrome c on oxidation of all the substrates studied, except of NADH, were increased in ischemia. The data obtained suggest that alterations in the mitochondria functional activity in ischemia occur due to an increase in penetration of pyridine nucleotides across the inner membrane and of cytochrome c across the outer layer. Heterogeneity of mitochondria is discussed.
