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Biomedical subjects

H Tedeschi

Publications and source records attributed to H Tedeschi.

65 records · Page 4Linked to original sources
PubMed1974

Mitochondrial membrane potential: evidence from studies with a fluorescent probe.

The fluorescence of the probe 3,3'-dihexyl-2,2'-oxacarbocyanine (CC(6)) has been found to indicate potential across cell membranes. Results obtained in the present study using CC(6) and Drosophila mitochondria are in agreement with membrane potentials previously measured by Tupper and Tedeschi using microelectrodes. The results of both studies with Drosophila suggest that the potential across the mitochondrial membrane does not play a significant role in oxidative phosphorylation.

Acetates↗
PubMed1970

Ion transport underlying metabolically controlled volume changes of isolated mitochondria.

An earlier study has indicated that the swelling of isolated mitochondria induced by inorganic phosphate (P(i)) can be accounted for largely or completely by the accumulation of ions. In the present study, a similar uptake was shown to be induced by a wider range of P(i) concentrations. Addition of ADP, KCN, or 2,4-dinitrophenol initiates a shrinkage which can be accounted for by the efflux of ions. The results are consistent with the explanations that (a) P(i) induces a transport of ions and a concomitant osmotic swelling, and (b) the addition of substances which compete or interfere with the energy available for transport results in ion efflux and a corresponding mitochondrial shrinkage. The results are not consistent with proposals that the changes in the light scattered by mitochondrial suspensions with alterations in metabolic states reflect a mechanochemical coupling phenomenon.

Adenine Nucleotides↗
PubMed1969

Microelectrode studies on the membrane properties of isolated mitochondria.

The membrane potentials and resistances of isolated Drosophila mitochondria were measured after impalement with piezoelectric-driven microelectrodes. The potential is approximately +10 mv (positive inside), and the membrane resistance is approximately 2Omega.cm(2) under state 4 conditions. Experiments involving changes in external osmolality at constant ionic strength have suggested that the measured potential is across the mitochondrial semipermeable membrane. The mitochondria generally collapse seconds after impalement. In cases of successive impalements, potential and resistance values show slight decreases from the initial impalements.

Animals↗
PubMed1969

Microelectrode studies on the membrane properties of isolated mitochondria. II. Absence of a metabolic dependence.

Mitochondrial membrane potentials and resistances have been determined under various metabolic conditions by the use of piezoelectric-driven microelectrodes. The mean state 3 potentials (about +19 mv) are higher than the potentials in state 4 (about +9 mv). DNP in uncoupling concentrations or KCN have no significant effect on membrane resistance or potential. Previous experiments have shown the potential to be sensitive to mitochondrial swelling and have suggested that it depends predominantly on anionic distribution.

Adenine Nucleotides↗
PubMed1968

Studies on the permeability of calf thymus nuclei isolated in sucrose.

A study of the permeability of calf thymus nuclei isolated in sucrose was carried out with sucrose-14C, glycerol-14C, and carboxydextran-14C (molecular weight, 60,000-90,000). The results indicate that the nuclei are very permeable to both sucrose and glycerol but they exclude the carboxydextran. Results obtained with other low molecular weight non-electrolytes (malonamide-14C, erythritol-14C, D-arabinose-14C, and D-mannitol-14C) are in agreement with the view that the nuclei are freely permeable to these molecular species. A sucrose-impermeable space is also present in these preparations and it has been attributed to the presence of intact cells. The high permeability of nuclei to sucrose was confirmed with Ficoll-separated preparations. The possibility of the presence of a substantial particulate space that allows the penetration of dextran cannot be excluded by these experiments, and this space may correspond to damaged nuclei.

Animals↗