Interference by cytochromes in the measurement of calcium with murexide

Scott, Ian G.; Jeacocke, Robin E.

doi:10.1016/0014-5793(80)81318-4

Cited by 6 publications

(1 citation statement)

References 20 publications

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“…To avoid spectral interference from cytochrome b reduction (19), we positioned the mitochondria out of the path of the measuring beams of the spectrophotometer by the method described above. To test the exchange rate of added Ca2, in the reaction medium with the top layer, we carefully injected 20 nmol of Ca2, just below the top layer in such a way as to minimize turbulent mixing and then monitored the &AAO-0.J7 nm of the upper layer.…”

Section: Resultsmentioning

confidence: 99%

Phytochrome induces photoreversible calcium fluxes in a purified mitochondrial fraction from oats

Roux

McEntire

Slocum

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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Previous studies have indicated that phytochrome regulates Ca2" fluxes across the plasma membrane of plant cells. In this study we investigated whether phytochrome can also regulate such fluxes across mitochondrial membranes, using the Ca2"-sensitive dye murexide to monitor the uptake and release of Ca2" by mitochondria. The results showed that Ca2" fluxes in these organelles could be photoreversibly altered, red light diminishing the net uptake rate and far-red light restoring this rate to its dark control level. Treatment ofthe mitochondria with ruthenium red blocked their Ca2+ uptake. In the presence of this inhibitor, red light induced a net efflux of Ca2`from the mitochondria, and subsequent far-red light reduced this efflux to nearly zero, the dark control level. Light-induced rate changes in Ca2`flux, both with and without the inhibitor, persisted for several minutes in the dark and remained photoreversible through several irradiations for as long as 30 min. The purity of the mitochondrial preparation wasjudged to be about 80% by electron microscopic morphometry; most of the phytochrome present was localized on the mitochondria in the preparation by using immunocytochemical methods. Taken together with previous findings, the results suggest that red light activation of phytochrome would initiate an increase in the cytosolic Ca2`concentration. The results are integrated with the fact that calmodulin is a component ofplant cell cytoplasms to construct a model postulating that phytochrome directs photomorphogenesis in part through its regulation of Ca2+ and calmodulin-controlled enzyme activities.

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Section: Resultsmentioning

confidence: 99%

Phytochrome induces photoreversible calcium fluxes in a purified mitochondrial fraction from oats

Roux

McEntire

Slocum

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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Impairment of ATP‐linked reactions in mitochondria isolated from skeletal muscle of halothane‐sensitive pigs

Ayoub¹,

Monin²,

Rock³

et al. 1990

Cell Biochemistry & Function

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Oxygen consumption was depressed in mitochondria isolated from halothane sensitive pig (HP) muscle. The calculation of the respiratory control ratio (RCR) indicated that mitochondria were more affected at the site-I level of the respiratory chain. Calcium accumulation in these mitochondria was not altered when driven by the oxidation of succinate. This process was abolished when linked to ATP as a source of energy. ATP transport was completely inhibited in (HP) mitochondria.

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