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Biomedical subjects

E Carafoli

Publications and source records attributed to E Carafoli.

At least 307 records · Page 17Linked to original sources
PubMed1975

The role of mitochondria in the contraction-relaxation cycle and other Ca2+-dependent activities of heart cells.

The problem of whether mitochondria participate in the contraction and relaxation of heart by binding Ca2+ reversibly has been discussed actively in recent times. The role of mitochondria has not yet been conclusively established, but is suggested by several lines of evidence, particularly in amphibian hearts. Apart from contraction and relaxation, the Ca2+ transport system of mitochondria may influence many Ca2+-sensitive cell reactions. Some are mitochondrial (succinate oxidase, alpha-glycerophosphate dehydrogenase, pyruvate dehydrogenase phosphate phosphatase) and may control the operations of the respiratory chain and of the trichloroacetic acid cycle. Among the extramitochondrial Ca2+-sensitive reactions are phosphorylase b kinase, phospholipases, and pyruvate kinase. The latter activity has been studied in detail, and it has indeed been found that it can be modulated by mitochondria. It appears possible that the mitochondrial system for binding and transporting Ca2+ is an efficient means to regulate various phases of cell metabolism.

Animals↗
PubMed1971

A survey of the interaction of calcium ions with mitochondria from different tissues and species.

A survey was made of the capacity of mitochondria isolated from a number of different tissues and species to accumulate Ca(2+) from the suspending medium during electron transport. The species examined included the rat, mouse, rabbit, hamster, guinea pig, cow, chicken, turtle, blowfly, yeast and Neurospora crassa. The tissues examined included vertebrate liver, kidney, brain, heart, spleen, thyroid and adrenal cortex, and the flight muscle of the blowfly. The mitochondria from all vertebrate tissues examined showed: (a) stimulation of State 4 respiration by added Ca(2+) (Ca(2+)/~ activation ratio about 2.0), accompanied by accumulation of Ca(2+) and ejection of H(+), with a H(+)/Ca(2+) ratio about 1.0; (b) a requirement of phosphate for accumulation of large amounts of Ca(2+); (c) respiration-independent high-affinity binding sites for Ca(2+); (d) endogenous Ca(2+), which is largely released by uncoupling agents. However, mitochondria from yeast and blowfly flight muscle are unable to accumulate Ca(2+) in a respiration-dependent process and possess no high-affinity Ca(2+)-binding sites. These findings support the view that the high-affinity sites represent the ligand-binding sites of a specific Ca(2+) ;permease' or transport system in the membrane. The relatively high affinity for Ca(2+), which equals or exceeds the affinity for ADP, and the generally uniform characteristics of Ca(2+) transport in all the vertebrate mitochondria tested strongly suggest that respiration-linked Ca(2+) accumulation plays a general and fundamental role in vertebrate cell physiology.

Adrenal Glands↗