Kinetics of nucleotide transport in rat heart mitochondria studied by a rapid filtration technique

Biochemistry ◽  
1990 ◽  
Vol 29 (41) ◽  
pp. 9720-9727 ◽  
Author(s):  
Gerard Brandolin ◽  
Isabelle Marty ◽  
Pierre V. Vignais
Keyword(s):  
Rat Heart ◽  
Heart Mitochondria ◽  
Rat Heart Mitochondria ◽  
Kinetics Of ◽  
Filtration Technique

scholarly journals The mitochondrial pyruvate carrier. Kinetics and specificity for substrates and inhibitors

1975 ◽  
Vol 148 (1) ◽  
pp. 85-96 ◽  
Author(s):  
A P Halestrap
Keyword(s):  
Rat Heart ◽  
Competitive Inhibitor ◽  
Structural Features ◽  
Heart Mitochondria ◽  
Aromatic Side Chain ◽  
Mitochondrial Pyruvate Carrier ◽  
Transport Inhibitors ◽  
Rat Heart Mitochondria ◽  
Rate Limiting ◽  
Kinetics Of

1. Studies on the kinetics of pyruvate transport into mitochondria by an ‘inhibitor-stop’ technique were hampered by the decarboxylation of pyruvate by mitochondria even in the presence of rotenone. Decarboxylation was minimal at 6 degrees C. At this temperature the Km for pyruvate was 0.15 mM and Vmax. was 0.54nmol/min per mg of protein; α-cyano-4-hydroxycinnamate was found to be a non-competitive inhibitor, Ki 6.3 muM, and phenyl-pyruvate a competitive inhibitor, Ki 1.8 mM. 2. At 100 muM concentration, α-cyano-4-hydroxycinnamate rapidly and almost totally inhibited O2 uptake by rat heart mitochondria oxidizing pyruvate. Inhibition could be detected at concentrations of inhibitor as low as 1 muM although inhibition took time to develop at this concentration. Inhibition could be reversed by diluting out the inhibitor. 3. Various analogues of α-cyano-4-hydroxycinnamate were tested on rat liver and heart mitochondria. The important structural features appeared to be the α-cyanopropenoate group and the hydrophobic aromatic side chain. α-Cyanocinnamate, α-cyano-5-phenyl-2,4-pentadienoate and compound UK 5099 [α-cyano-β-(2-phenylindol-3-yl)acrylate] were all more powerful inhibitors than α-cyano-4-hydroxycinnamate showing 50% inhibition of pyruvate-dependent O2 consumption by rat heart mitochondria at concentrations of 200, 200 and 50 nM respectively. 4. The specificity of the carrier for its substrate was studied by both influx and efflux experiments. Oxamate, 2-oxobutyrate, phenylpyruvate, 2-oxo-4-methyl-pentanoate, chloroacetate, dichloroacetate, difluoroacetate, 2-chloropropionate, 3-chloropropionate and 2,2-dichloropropionate all exchanged with pyruvate, whereas acetate, lactate and trichloroacetate did not. 5. Pyruvate entry into the mitochondria was shown to be accompanied by the transport of a proton (or by exchange with an OH-ion). This proton flux was inhibited by α-cyano-4-hydroxycinnamate and allowed measurements of pyruvate transport at higher temperatures to be made. The activation energy of mitochondrial pyruvate transport was found to be 113 kJ (27 kcal)/mol and by extrapolation the rate of transport of pyruvate at 37 degrees C to be 42 nmol/min per mg of protein. The possibility that pyruvate transport into mitochondria may be rate limiting and involved in the regulation of gluconegenesis is discussed. 6. The transport of various monocarboxylic acids into mitochondria was studied by monitoring proton influx. The transport of dichloroacetate, difluoroacetate and oxamate appeared to be largely dependent on the pyruvate carrier and could be inhibited by pyruvate-transport inhibitors. However, many other halogenated and 2-oxo acids which could exchange with pyruvate on the carrier entered freely even in the presence of inhibitor.

scholarly journals Actions of the creatine analogue β-guanidinopropionic acid on rat heart mitochondria

1994 ◽  
Vol 300 (1) ◽  
pp. 211-216 ◽  
Author(s):  
J F Clark ◽  
Z Khuchua ◽  
A V Kuznetsov ◽  
E Vassil'eva ◽  
E Boehm ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Isolated Cardiomyocytes ◽  
Isolated Mitochondria ◽  
Significant Stimulation ◽  
Ionic Detergent ◽  
Rat Heart Mitochondria ◽  
Kinetics Of ◽  
Stimulation Of

The action of the creatine analogue beta-guanidinopropionic acid (beta-GPA) was examined in rat heart mitochondria and in isolated cardiomyocytes or fibres which were permeabilized with the non-ionic detergent saponin to determine the kinetics of mitochondrial creatine kinase for beta-GPA. Fibres and myocytes were subjected to increasing [ADP] in the presence and absence of beta-GPA or creatine, whereas isolated mitochondria received a similar protocol with increasing [ATP]. In isolated mitochondria given ATP, there was a stimulation of respiration by creatine, but no significant stimulation of respiration by beta-GPA. Further studies on fibres from control and beta-GPA-fed rats also found that beta-GPA is not utilized by the mitochondria, as evidenced by a lack of beta-GPA-stimulated respiration (Km for ADP = 142 +/- 23 microM) compared with control (Km for ADP from 161 +/- 23 microM), but no significant change in Vmax. Therefore the rat heart mitochondria are not responsive to beta-GPA as compared with creatine. Interestingly, the fibres from beta-GPA-fed rats had no creatine- or beta-GPA-stimulated respiration (Km for ADP = 57.3 +/- 7.2 microM for control, 54.2 +/- 7.2 microM with creatine, and 53.5 +/- 7.8 microM with beta-GPA). The mitochondria prepared from the hearts of rats exposed for 10 weeks to 1% beta-GPA in their diet had a significant decrease in Vmax. and a significant decrease in Km for ADP. Thus the hearts from beta-GPA-fed animals may be pathologic, due to a disruption of the creatine kinase energy circuit.

Magnolol and honokiol isolated from magnolia officinalis protect rat heart mitochondria against lipid peroxidation

1994 ◽  
Vol 47 (3) ◽  
pp. 549-553 ◽  
Author(s):  
Yu-Chiang Lo ◽  
Teng Che-Ming ◽  
Chen Chieh-Fu ◽  
Chen Chien-Chih ◽  
Hong Chuang-Ye
Keyword(s):  
Lipid Peroxidation ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Rat Heart Mitochondria ◽  
Magnolia Officinalis

Involvement of SH-groups during interaction of diazoxide with the inner membrane of rat heart mitochondria

2007 ◽  
Vol 415 (1) ◽  
pp. 206-210 ◽  
Author(s):  
S. M. Korotkov ◽  
V. P. Nesterov ◽  
L. V. Emel’yanova ◽  
N. N. Ryabchikov
Keyword(s):  
Rat Heart ◽  
Heart Mitochondria ◽  
Inner Membrane ◽  
Sh Groups ◽  
Rat Heart Mitochondria

Abstract 104: Effects of Pinacidil and Ca 2 + on Sodium-loaded Rat Heart Mitochondria

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Sergey M Korotkov ◽  
Vladimir P Nesterov ◽  
Irina V Brailovskaya ◽  
Larisa V Emelyanova ◽  
Svetlana A Konovalova ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Rat Heart ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion ◽  
Potassium Acetate ◽  
Heart Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Rat Heart Mitochondria ◽  
Acetate Medium

Deterioration of the contractile parameters of the heart muscle caused by ischemia and followed reperfusion is known as the main postoperative complication which is related to Ca 2+ and Na + overload in cardiomyocytes and mitochondria. Pinacidil reduced the overload in ischemia/reperfusion experiments. The mechanism of this phenomenon is still not clear. We hypothesized that increased ion permeability of the inner mitochondrial membrane (IMM) followed drop of electrochemical potential (ΔΨ mito ) can reduce the calcium. The aim of the study was to elucidate the effect of pinacidil (100 μM) and Ca 2+ (100 μM ) on swelling, oxygen consumption and ΔΨ mito of isolated sodium-loaded rat heart mitochondria (RHM(Na)) energized glutamate and malate. Pinacidil significantly enchanced the permeability of IMM to protons in ammonium nitrate medium. Also increased swelling of RHM(Na) energized with substrates in potassium acetate medium revealed that pinacidil increased potassium transport into matrix. Pinacidil stimulated oxygen consumption of RHM(Na) in State 4 and detained Ca 2+ -induced dissipation of ΔΨ mito . Under condition of Ca 2+ and Na + overload simulating ischemia/reperfusion, RHM(Na) oxygen consumption was not affected with pinacidil in State 3 and in the presence of 2,4-dinitrophenol. Cyclosporin A and ADP, the inhibitors of mitochondrial permeability transition pore (MPTP), markedly decreased Ca 2+ - induced swelling of RHM(Na) in nitrate ammonium or potassium acetate medium in the presence of pinacidil. Carboxyatractyloside, an inhibitor of cytosolic side-specific adenine nucleotide translocase, eliminated a pinacidil-stimulated oxygen consumption of succinate-energized RHMNa in State 4 regardless of the presence of Ca 2+ . Pinacidil was also concluded to accelerat potassium flux into energized RHM(Na) and promot MPTP opening in the low conduction state. Based on our data we suggested that the effect of pharmacological preconditioning induced by pinacidil could be due to it’s direct effect on mitochondria which is connected with above stimulation of the potassium permeability of the inner mitochondrial membrane and following reduce of the ΔΨ mito that thus prevent calcium overload of cardiomyocytes after ischemia/reperfusion in turn.

Structure of paracrystalline arrays on outer membranes of rat-liver and rat-heart mitochondria

1992 ◽  
Vol 108 (3) ◽  
pp. 227-237 ◽  
Author(s):  
C.A. Mannella ◽  
A. Ribeiro ◽  
B. Cognon ◽  
D. D'Arcangelis
Keyword(s):  
Rat Liver ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Outer Membranes ◽  
Rat Heart Mitochondria
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