The oxygen dependence of mitochondrial respiration was investigated using suspensions of mitochondria and quiescent ventricular myocytes isolated from adult rat hearts. A new optical method was used to determine oxygen concentration in the suspending media. The P50 for respiration for coupled mitochondria at a high [ATP]/[ADP].[Pi] ratio and oxidizing glutamate/malate was 0.45 +/- 0.03 microM b...

Speract (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-ValGly), a Tyr analogue ("'yr-Asp-Leu-Asn-Gly-Gly-GlyVal-Gly), carboxyl-terminal fragment (Gly-Gly-GlyVal-Gly), and an NHz-terminaI fragment (Gly-Phe-AspLeu-Asn-Gly-Gly-Gly) were tested for their effects on sea urchin sperm respiration and net H+ efflux. The stimulation of net H' efflux by these peptides was highly correlated with their ability to sti...

The influence of graded x-ray doses upon nitrogen fixation and respiration by Azotobacter was studied by means of the Warburg method. It was found that nitrogen fixation decreases approximately linearly with increasing x-ray doses. Respiration in contrast is affected only indirectly through some inhibition of cell multiplication. Small doses of x-ray often produce a slight and transient increas...

The action of growth substances in causing cell elongation is closely linked to respiration, and many respiratory inhibitors also inhibit growth (COMMONER and THIMANN, 3, BONNER, 1, 2). In the study -of the way in which growth substances act to bring about growth it is therefore useful to have inhibitors which will suppress the action of growth substances without affecting respiration of the tr...

During sepsis, liver dysfunction is common, and failure of mitochondria to effectively couple oxygen consumption with energy production has been described. In addition to sepsis, pharmacological agents used to treat septic patients may contribute to mitochondrial dysfunction. This study addressed the hypothesis that remifentanil interacts with hepatic mitochondrial oxygen consumption. The human...

The metabolic control of respiration is still poorly understood, due mainly to the lack of suitable approaches for studying it in vivo. Experiments on isolated mammalian mitochondria have indicated that a relatively small fraction of each of several components of the electron transport chain is sufficient to sustain a normal O2 consumption rate. These experiments, however, may not reflect accur...

Endogenously produced nitric oxide (NO) interacts with mitochondrial cytochrome c oxidase, leading to inhibition of cellular respiration. This interaction has been shown to have important physiological and pathophysiological consequences. Exogenous carbon monoxide (CO) is also known to inhibit cytochrome c oxidase in vitro; however, it is not clear whether endogenously produced CO can inhibit c...

To gain insight into the regulation of pancreatic beta-cell mitochondrial metabolism, the direct effects on respiration of different mitochondrial substrates, variations in the ATP/ADP ratio and free Ca2+ were examined using isolated mitochondria and permeabilized clonal pancreatic beta-cells (HIT). Respiration from pyruvate was high and not influenced by Ca2+ in State 3 or under various redox ...

In the present work, Jurkat cells undergoing anti-Fas antibody (anti-Fas)-triggered apoptosis exhibited in increasing proportion a massive release of cytochrome c from mitochondria, as revealed by double-labeling confocal immunofluorescence microscopy. The cytochrome c release was followed by a progressive reduction in the respiratory activity of the last respiratory enzyme, cytochrome c oxidas...