Biomedical subjects

H Nagamune

Publications and source records attributed to H Nagamune.

39 records · Page 3Linked to original sources

PubMed1983

A cyanine dye tri-S-C7(5). Phosphate-dependent cationic uncoupler of oxidative phosphorylation in mitochondria.

The trinuclear cyanine dye, tri-S-C7(5), at about 10 microM stimulated State 4 respiration of rat liver mitochondria more than 6-fold and released oligomycin-inhibited respiration completely. Thus, the dye is concluded to be a very effective cationic uncoupler of oxidative phosphorylation in mitochondria. However, for exhibition of its uncoupling action, the presence of Pi (or arsenate) was necessary, and a phosphate-transport inhibitor, N-ethylmaleimide or mersalyl, inhibited its action. The stimulation of phosphate transport via the Pi carrier by the dye is suggested to be directly related to the uncoupling action.

Animals↗

PubMed1983

The cyanine dye triS-C4(5) as a cationic uncoupler of oxidative phosphorylation: interaction with mitochondria detected by derivative spectrophotometry.

Derivative spectrophotometry was used to study the interaction of the cationic uncoupler triS-C4(5) with mitochondria. The uncoupling action of this dye is dependent on the presence of Pi in the incubation medium. The second derivative spectrum of the dye changed with the incubation period, becoming similar to the spectrum in chloroform; but, after a time, the spectral pattern reverted to the original spectrum. The change in the spectrum in the presence of Pi was much more rapid than in its absence. The degree of spectral change agreed with the relative amount of bound dye determined directly. Thus, the spectral change reflects the binding of dye to the mitochondria, dependent on their energy state. The greater binding without Pi does not cause uncoupling but does cause shrinkage. In contrast, the lesser binding in the presence of Pi causes uncoupling and the swelling of mitochondria. These facts indicate that the dye does not penetrate the mitochondrial membrane. This refutes the idea that uncoupling by lipophilic cations is caused by the electrophoretic transfer of the uncoupler to the mitochondrial matrix space.

Animals↗

PubMed1981

Specific requirement for inorganic phosphate for induction of bilayer membrane conductance by the cationic uncoupler carbocyanine dye.

The trinucleous divalent cationic cyanine dye triS-C4(5) was shown to be an uncoupler of oxidative phosphorylation in mitochondria only in reaction medium containing inorganic phosphate (Pi). This dye also induced marked increase in the electrical conductance of a phospholipid bilayer membrane in bathing solution containing Pi, but not in solution containing Tris-HCl buffer without Pi. Time-dependent fluctuation of the electrical current across the bilayer membrane was observed in the presence of triS-C4(5) only in bathing solution containing Pi. This fluctuation could be due to perturbation of the bilayer membrane structure induced by the cooperative action of the cyanine dye and Pi, and this perturbation should be directly related to their effects in increasing membrane conductance and also causing uncoupling in mitochondria.

Animals↗