Calcium immobilization in mitochondria of failing myocardium: X-ray microanalytical evidence

Diculescu, I; Ionescu, N; Popescu, L. M.

doi:10.1016/0022-2828(78)90358-9

Cited by 7 publications

(2 citation statements)

References 18 publications

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“…T h e precise significance of the mitochondria as a calcium reservoir in normal myocardium thus remains unclear. Changes in calcium distribution over mitochondria from damaged myocardial cells were also reported by Trump et al (1978) and Diculescu, Ionescu & Popescu (1978).…”

Section: (Ii) Musclesupporting

confidence: 71%

“…If, on the other hand, ultrathin sections of frozen, unfixed heart were cut at -90 O C and freeze-dried, the mitochondria contained smaller, spherical particles varying in size from 25-40 nm in human to 60-90 nm in mouse heart. Changes in calcium distribution over mitochondria from damaged myocardial cells were also reported by Trump et al (1978) and Diculescu, Ionescu & Popescu (1978). T h e idea was put forward that the mitochondria do sequester calcium, but that it is insufficiently bound to survive chemical fixation.…”

Section: (Ii) Musclementioning

confidence: 56%

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Electron‐probe X‐ray Microanalysis: Techniques and Recent Applications in Biology

Moreton¹

1981

Biological Reviews

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Summary (1) X‐ray microanalysis is a powerful technique, allowing the quantitative measurement of many elements of physiological interest, at physiological concentrations and with a spatial resolution typically of a few micrometres in bulk specimens, and a few hundred nanometres in thin sections. (2) The basic requirements are a focussed, high‐energy electron beam, X‐ray spectrometers and a means of visualizing the specimen. These facilities are found in a number of different types of commercial microanalysers, which may be based on either the transmission electron microscope, or the scanning electron microscope. Scanning microanalysers offer a lower image resolution, but are considerably more versatile than instruments based on the transmission electron microscope. (3) Preparing the specimen in a form that will withstand electron bombardment under high vacuum, and yet in which the elements to be analysed are retained in their original locations, is clearly the most critical step. For analysing diffusible elements, especially water‐soluble electrolytes, the only reliable method is to freeze as rapidly as possible, and analyse the tissue without any chemical treatment. (4) The best results are obtained if frozen sections are cut and analysed on a cold‐stage with their water content retained as ice. Procedures have been worked out for doing this, and for quantitative interpretation of the results, so that original tissue concentrations of the common electrolytes, phosphorus, sulphur and other elements of interest can now be measured with confidence. The original water‐content of different cell and tissue compartments can also be estimated from the mass‐loss on drying. (5) A simpler alternative is to freeze‐dry the frozen sections before analysis. The distribution of diffusible elements is probably not too much disturbed, spatial resolution is improved, and the visual image becomes much clearer, but quantitation is made more difficult and less reliable. Nevertheless this technique is frequently used. (6) For precipitated materials and for fluid samples, much simpler methods of preparation can be used. (7) The technique is the subject of a large and rapidly expanding literature, and is providing new information on the sub‐cellular distribution of electrolytes and other elements in many different tissues from animals and plants. (8) Some of the earliest applications to the study of diffusible ions were in the analysis of micropuncture samples from kidney tubules, where it has been possible to analyse many very small samples, and for several elements at once. Some preliminary information has also been obtained on the intracellular ion concentrations in kidneys subjected to different physiological conditions. (9) A particularly successful field has been the study of transporting epithelia, including vertebrate and insect digestive and excretory tissues, where the distribution of ions along the intercellular spaces has been shown not to agree with that predicted from the ‘standing gradient’ theory of osmotic coupling. Th...

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Section: (Ii) Musclesupporting

confidence: 71%

Section: (Ii) Musclementioning

confidence: 56%

Electron‐probe X‐ray Microanalysis: Techniques and Recent Applications in Biology

Moreton¹

1981

Biological Reviews

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Influence of intracellular pH on mitochondrial calcium during ischaemia of the isolated rat heart

1989

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Under physiological conditions cardiac mitochondria seem to play a minor role in maintaining intracellular Ca2+ homoeostasis. However, under conditions of cellular Ca2+ overload, mitochondria may accumulate large amounts of Ca2+. Using transmission and analytical electron microscopy, we investigated, in globally ischaemic rat heart preparations, the influence of intracellular pH on the development of Ca2+-containing intramitochondrial inclusions. We confirmed that under these experimental conditions Ca2+ was a major element of mitochondrial inclusions. The size of these inclusions increased with external Ca2+ concentration. An intracellular alkalinization, produced by addition of 20 mM NH4Cl to the perfusate prior to ischaemia, inhibited the formation of such inclusions. On the other hand, a pre-ischaemic intracellular acidification, produced by the addition and subsequent withdrawal of the 20 mM NH4Cl, increased the number of inclusions present at the end of an ischaemic episode. The presence of amiloride (10(-3) M), prior to and during ischaemia, increased the number of inclusions. These data suggest that cytoplasmic pH may be an important factor in mitochondrial Ca2+ accumulation in pathological conditions.

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Localization artefacts in ultracytochemical ion precipitation reactions

Zglinicki

Punkt

1986

Histochem J

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The precipitation patterns of the following ultracytochemical methods in rat muscle cells were compared and examined critically: the potassium pyroantimonate method for calcium demonstration; the calcium phosphate technique for the Ca2+--ATPase reaction; the formazan reaction for the demonstration of creatine kinase activity (all performed on heart muscle); and the lead phosphate technique for the Mg2+--ATPase reaction in skeletal muscle. Using X-ray microanalysis, it was found that the antimonate precipitate contains only calcium as the precipitated ion in the vast majority of cases. Most probably it consists of pure calcium pyroantimonate. However, in myocytes showing the well-established precipitation pattern, the concentration of calcium was estimated to be about two orders of magnitude higher than the native concentration of total intracellular calcium. It is concluded that calcium ions diffuse freely from the extracellular space and from adjacent cells into cells containing antimonate and are precipitated mostly at sites where heterogeneous nucleation is facilitated by intracellular catalysts (biopolymers). As shown by the similar precipitation patterns for the four reactions compared, these catalysts are not specific to any of these reactions and are most probably neither calcium-binding sites nor sites of any one of the enzymes examined in the native cell.

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Calcium immobilization in mitochondria of failing myocardium: X-ray microanalytical evidence

Cited by 7 publications

References 18 publications

Electron‐probe X‐ray Microanalysis: Techniques and Recent Applications in Biology

Electron‐probe X‐ray Microanalysis: Techniques and Recent Applications in Biology

Influence of intracellular pH on mitochondrial calcium during ischaemia of the isolated rat heart

Localization artefacts in ultracytochemical ion precipitation reactions

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