Calcium and proton transport in chromaffin granule membranes: a proton NMR study

Yoon, Poksyn S.; Sharp, Robert R.

doi:10.1021/bi00346a037

Cited by 8 publications

(3 citation statements)

References 23 publications

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“…Both systems are sensitive to inhibitors of mitochondria1 ATPase and the respiratory chain. However, a recent study using nuclear magnetic resonance (Yoon and Sharp, 1985) suggests that the calcium transport system of the CG membranes is not directly coupled to the transmembrane proton gradient. Furthermore, the CG ATPase has recently been purified and shown to be insensitive to the mitochondrial ATPase inhibitors sodium aide and oligomycin (Cidon and Nelson, 1986;Dean et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Calcium Homeostasis in Digitonin‐Permeabilized Bovine Chromaffin Cells

Kao

1988

Journal of Neurochemistry

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The regulation of cytosolic calcium was studied in digitonin-permeabilized chromaffin cells. Accumulation of 45Ca2+ by permeabilized cells was measured at various Ca2+ concentrations in the incubation solutions. In the absence of ATP, there was a small (10-15% of total uptake) but significant increase in accumulation of Ca2+ into both the vesicular and nonvesicular pools. In the presence of ATP, the permeabilized cells accumulated Ca2+ into carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-sensitive and -insensitive pools. The CCCP-sensitive pool--mainly mitochondria--was active when the calcium concentration was greater than 1 microM and was not saturated at 25 microM. The Ca2+ sequestered by the CCCP-insensitive pool could be inhibited by vanadate and released by inositol trisphosphate, a combination suggesting that this pool was the endoplasmic reticulum. The CCCP-insensitive pool had a high affinity for calcium, with an EC50 of approximately 1 microM. When the Ca2+ concentration was adjusted to the level in the cytoplasm of resting cells (0.1 microM), the presumed endoplasmic reticulum pool was responsible for approximately 90% of the ATP-stimulated calcium uptake. At a calcium level similar to the acetylcholine-stimulated level in intact cells (5-10 microM), most of the Ca2+ (greater than 95%) went into the CCCP-sensitive pool.

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Section: Discussionmentioning

confidence: 99%

Calcium Homeostasis in Digitonin‐Permeabilized Bovine Chromaffin Cells

Kao

1988

Journal of Neurochemistry

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“…that K+ efflux matched HI influx, but not Na+ influx, on oxygenation of yeast cells. Yoon & Sharp (1985) established that Ca2+ influx is not linked to HI efflux in chromaffin granules. In leaf cells, n.m.r.…”

Section: Spin Label Probe Methods Transmembrane Lipid Asymmetrymentioning

confidence: 99%

Magnetic resonance of membranes

Knowles

Marsh

1991

Biochemical Journal

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“…For example, efforts to find a calcium ATPase in chromaffin granule limiting membrane have been largely unsuccessful (27). Because of the acid interior of chromaffin granules (and other secretory granules), proton/calcium antiport activity was sought, but could not be demonstrated (28). These latter investigators suggested that calcium accumulation was due to sodium/calcium exchange, but more recent studies using EPMA of in situ chromaffin granules failed to show the existence of the necessary sodium gradient (29).…”

Section: Discussionmentioning

confidence: 99%

Perinatal changes in lung surfactant calcium measured in situ.

Eckenhoff¹

1989

J. Clin. Invest.

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Calcium ion is thought to play a role in the structure and function of pulmonary surfactant after secretion into the alveolar space. Since fetal lung liquid calcium concentration is inadequate for this hypothesized role, at a time when optimal surfactant function is necessary for survival, we speculated that the necessary calcium is secreted with the surfactant material, i.e., in the lamellar body. Lungs from rat fetuses at 20, 21, and 22 d gestation, and also from newborn rats at 3-5 h, 1 and 3 d, were rapidly frozen, sectioned, freeze-dried, and examined cold (-100°C) in a transmission electron microscope equipped with a fully quantitative energy-dispersive x-ray detector and analyzer. X-ray spectra were collected from the lamellar bodies and cytoplasm of type II cells at each time point. Lamellar body calcium concentration in the fetus was approximately twice that of the adult (70±4 vs. 37±2 mmol/kg dry wt±SEM, P < 0.01), and it decreased rapidly after birth to adult levels. Apically located lamellar bodies in the fetus have a significantly higher calcium concentration than those in a perinuclear position (76±4 vs. 52±3, P < 0.01). There is a significant correlation of calcium and chloride concentrations in lamellar bodies, suggesting that factors responsible for the distribution of chloride, i.e., pH, may also be responsible for the accumulation of calcium by these organelles. These results show that mature calcium transport in lamellar bodies is achieved prenatally in the rat, and suggest that the calcium required for normal surfactant function at birth is secreted with the lamellar body.

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Calcium and proton transport in chromaffin granule membranes: a proton NMR study

Cited by 8 publications

References 23 publications

Calcium Homeostasis in Digitonin‐Permeabilized Bovine Chromaffin Cells

Calcium Homeostasis in Digitonin‐Permeabilized Bovine Chromaffin Cells

Magnetic resonance of membranes

Perinatal changes in lung surfactant calcium measured in situ.

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