Mechanism of proton-induced bone calcium release: calcium carbonate-dissolution

1987 ◽  
Vol 253 (5) ◽  
pp. F998-F1005 ◽  
Author(s):  
D. A. Bushinsky ◽  
R. J. Lechleider
Keyword(s):  
Metabolic Acidosis ◽  
Calcium Carbonate ◽  
Bone Mineral ◽  
Calcium Release ◽  
Calcium Efflux ◽  
Carbonate Phase ◽  
Bone Calcium ◽  
Calcium Carbonate Dissolution

Protons are buffered and calcium is released by bone during metabolic acidosis. Incubation of neonatal mouse calvariae in acid medium causes net calcium efflux from bone and net proton influx into bone, just as metabolic acidosis does in vivo. To determine whether the calcium carbonate phase of bone mineral is solubilized with increasing proton concentrations, we cultured calvariae for 3 h in medium in which the saturation was varied by changing pH or calcium and phosphate concentrations. We determined the driving force for crystallization by calculating the Gibbs free energy of formation (DG). With alteration of the medium pH, calcium carbonate entry or loss from bone varied linearly with the initial DG for medium calcium carbonate (r = -0.745, n = 41, P less than 0.001) as it did with alteration of the medium calcium and phosphate (r = -0.665, n = 118, P less than 0.001). There was dissolution of calcium carbonate into medium that was unsaturated with respect to calcium carbonate, net flux ceased at saturation, and calcium carbonate entered bone from supersaturated medium, indicating that the medium is in equilibrium with the calcium carbonate phase of bone mineral. Neither the mineral phase brushite nor apatite was in equilibrium with the medium. These observations indicate that in vitro, acute proton-induced calcium efflux is due to dissolution of bone calcium carbonate.

Metabolic alkalosis decreases bone calcium efflux by suppressing osteoclasts and stimulating osteoblasts

1996 ◽  
Vol 271 (1) ◽  
pp. F216-F222 ◽  
Author(s):  
D. A. Bushinsky
Keyword(s):  
Bone Mineral ◽  
Metabolic Alkalosis ◽  
Collagen Synthesis ◽  
Cell Function ◽  
Urinary Calcium ◽  
Calcium Excretion ◽  
Calcium Efflux ◽  
Medium Ph ◽  
Bone Calcium

In vivo and in vitro evidence indicates that metabolic acidosis, which may occur prior to complete excretion of end products of metabolism, increases urinary calcium excretion. The additional urinary calcium is almost certainly derived from bone mineral. Neutralization of this daily acid load, through the provision of base, decreases calcium excretion, suggesting that alkali may influence bone calcium accretion. To determine whether metabolic alkalosis alters net calcium efflux (JCa+) from bone and bone cell function, we cultured neonatal mouse calvariae for 48 h in either control medium (pH approximately equal to 7.4, [HCO3-] approximately equal to 24), medium simulating mild alkalosis (pH approximately equal to 7.5, [HCO3-] approximately equal to 31), or severe alkalosis (pH approximately equal to 7.6, [HCO3-] approximately equal to 39) and measured JCa+ and the release of osteoclastic beta-glucuronidase and osteoblastic collagen synthesis. Compared with control, metabolic alkalosis caused a progressive decrease in JCa+, which was correlated inversely with initial medium pH (pHi). Alkalosis caused a decrease in osteoclastic beta-glucuronidase release, which was correlated inversely with pHi and directly with JCa+. Alkalosis also caused an increase in osteoblastic collagen synthesis, which was correlated directly with pHi and inversely with JCa+. There was a strong inverse correlation between the effects alkalosis on osteoclastic beta-glucuronidase release and osteoblastic collagen synthesis. Thus metabolic alkalosis decreases JCa+ from bone, at least in part, by decreasing osteoclastic resorption and increasing osteoblastic formation. These results suggest that the provision of base to neutralize endogenous acid production may improve bone mineral accretion.

Effects of in vivo metabolic acidosis on midcortical bone ion composition

1999 ◽  
Vol 277 (5) ◽  
pp. F813-F819 ◽  
Author(s):  
David A. Bushinsky ◽  
Jan M. Chabala ◽  
Konstantin L. Gavrilov ◽  
Riccardo Levi-Setti
Keyword(s):  
Metabolic Acidosis ◽  
Bone Mineral ◽  
Calcium Absorption ◽  
Urinary Calcium ◽  
Calcium Excretion ◽  
Ion Composition ◽  
Arterial Blood Gas ◽  
Arterial Blood

Chronic metabolic acidosis increases urine calcium excretion without altering intestinal calcium absorption, suggesting that bone mineral is the source of the additional urinary calcium. During metabolic acidosis there appears to be an influx of protons into bone mineral, lessening the magnitude of the decrement in pH. Although in vitro studies strongly support a marked effect of metabolic acidosis on the ion composition of bone, there are few in vivo observations. We utilized a high-resolution scanning ion microprobe with secondary ion mass spectroscopy to determine whether in vivo metabolic acidosis would alter bone mineral in a manner consistent with its purported role in buffering the increased proton concentration. Postweanling mice were provided distilled drinking water with or without 1.5% NH4Cl for 7 days; arterial blood gas was then determined. The addition of NH4Cl led to a fall in blood pH and [Formula: see text] concentration. The animals were killed on day 7, and the femurs were dissected and split longitudinally. The bulk cortical ratios Na/Ca, K/Ca, total phosphate/carbon-nitrogen bonds [(PO2 + PO3)/CN], and[Formula: see text]/CN each fell after 1 wk of metabolic acidosis. Because metabolic acidosis induces bone Ca loss, the fall in Na/Ca and K/Ca indicates a greater efflux of bone Na and K than Ca, suggesting H substitution for Na and K on the mineral. The fall in (PO2 + PO3)/CN indicates release of mineral phosphates, and the fall in[Formula: see text]/CN indicates release of mineral[Formula: see text]. Each of these mechanisms would result in buffering of the excess protons and returning the systemic pH toward normal.

Net proton influx into bone during metabolic, but not respiratory, acidosis

1988 ◽  
Vol 254 (3) ◽  
pp. F306-F310 ◽  
Author(s):  
D. A. Bushinsky
Keyword(s):  
Metabolic Acidosis ◽  
Bone Mineral ◽  
Respiratory Acidosis ◽  
Mineral Dissolution ◽  
Calcium Efflux ◽  
Bicarbonate Concentration ◽  
Medium Ph ◽  
Acute Metabolic Acidosis ◽  
Initial Medium

During acute metabolic acidosis there is a net influx of protons into bone, decreasing the elevated proton concentration. Whether there is an influx of protons into bone during acute respiratory acidosis is not known. To determine the effect of respiratory acidosis on net proton flux (JH) relative to bone, we compared JH from neonatal mouse calvariae incubated for 3 h in medium acidified by an increase in PCO2 (respiratory acidosis) with that from calvariae incubated in medium acidified to the same extent by a decrease in bicarbonate concentration (metabolic acidosis). The initial medium pH with respiratory acidosis was not different from that with metabolic acidosis (7.108 +/- 0.005 vs. 7.091 +/- 0.007, respectively, P = NS). During respiratory acidosis there was no JH from bone relative to the medium (JH = 236 +/- 93 neq.bone-1.3h-1, P = NS vs. 0); however, during metabolic acidosis there was net proton influx from the medium into bone (JH = -703 +/- 108, P less than 0.05 vs. 0, P less than 0.001 vs. respiratory acidosis). There was less calcium efflux from bone during respiratory than during metabolic acidosis (JCa = 68 +/- 6 nmol.bone-1.3 h-1 vs. 100 +/- 9, respectively, P less than 0.001). There is a net influx of protons into bone in vitro during acute metabolic, but not during acute respiratory, acidosis. The smaller calcium efflux during respiratory acidosis may indicate less net bone mineral dissolution and thus less buffer release into the medium.

Cytotoxicity Studies of Curcumin Loaded-Cockle Shell-Derived Calcium Carbonate Nanoparticles

2019 ◽  
Vol 09 ◽  
Author(s):  
Maryam Muhammad Mailafiya ◽  
Mohamad Aris Mohd Moklas ◽  
Kabeer Abubakar ◽  
Abubakar Danmaigoro ◽  
Samaila Musa Chiroma ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Safety Margin ◽  
Bone Diseases ◽  
In Vivo Studies ◽  
Normal Cells ◽  
Cytotoxicity Studies ◽  
Standard Techniques ◽  
Cockle Shell

Background: Cockle shell-derived calcium carbonate nanoparticles (CSCaCO3NP) are natural biogenic inorganic material that is used in drug delivery mainly as a bone-remodeling agent as well as a delivery agent for various therapeutics against bone diseases. Curcumin possess wide safety margin and yet puzzled with the problem of poor bioavailability due to insolubility. Propounding in vitro and in vivo studies on toxicity assessments of newly synthesized nanoparticles are ongoing to overcome some crucial challenges regarding their safety administration. Nanotoxicology has paved ways for concise test protocols to monitor sequential events with regards to possible toxicity of newly synthesized nanomaterials. The development of nanoparticle with no or less toxic effect has gained tremendous attentions. Objective: This study aimed at evaluating the in vitro cytotoxic effect of curcumin-loaded cockle shell-derived calcium carbonate nanoparticles (Cur-CSCaCO3NP) and assessing its biocompatibility on normal cells using standard techniques of WST’s assay. Method: Standard techniques of WST’s assay was used for the evaluation of the biocompatibility and cytotoxicity. Result: The result showed that CSCaCO3NP and Cur-CSCaCO3NP possess minimal toxicity and high biocompatibility on normal cells even at higher dose of 500 µg/ml and 40 µg/ml respectively. Conclusion: CSCaCO3NP can be termed an excellent non-toxic nanocarrier for curcumin delivery. Hence, curcumin loaded cockle shell derived calcium carbonate nanoparticles (Cur-CSCaCO3NP) could further be assessed for various in vivo and in vitro therapeutic applications against various bone related ailments.

scholarly journals DJ-1 regulates the integrity and function of ER-mitochondria association through interaction with IP3R3-Grp75-VDAC1

2019 ◽  
Vol 116 (50) ◽  
pp. 25322-25328 ◽  
Author(s):  
Yi Liu ◽  
Xiaopin Ma ◽  
Hisashi Fujioka ◽  
Jun Liu ◽  
Shengdi Chen ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Cellular Mechanism ◽  
Loss Of Function ◽  
Wild Type ◽  
Calcium Efflux ◽  
And Function ◽  
The Brain ◽  
Early Onset Parkinson’S Disease

Loss-of-function mutations in DJ-1 are associated with autosomal recessive early onset Parkinson’s disease (PD), yet the underlying pathogenic mechanism remains elusive. Here we demonstrate that DJ-1 localized to the mitochondria-associated membrane (MAM) both in vitro and in vivo. In fact, DJ-1 physically interacts with and is an essential component of the IP3R3-Grp75-VDAC1 complexes at MAM. Loss of DJ-1 disrupted the IP3R3-Grp75-VDAC1 complex and led to reduced endoplasmic reticulum (ER)-mitochondria association and disturbed function of MAM and mitochondria in vitro. These deficits could be rescued by wild-type DJ-1 but not by the familial PD-associated L166P mutant which had demonstrated reduced interaction with IP3R3-Grp75. Furthermore, DJ-1 ablation disturbed calcium efflux-induced IP3R3 degradation after carbachol treatment and caused IP3R3 accumulation at the MAM in vitro. Importantly, similar deficits in IP3R3-Grp75-VDAC1 complexes and MAM were found in the brain of DJ-1 knockout mice in vivo. The DJ-1 level was reduced in the substantia nigra of sporadic PD patients, which was associated with reduced IP3R3-DJ-1 interaction and ER-mitochondria association. Together, these findings offer insights into the cellular mechanism in the involvement of DJ-1 in the regulation of the integrity and calcium cross-talk between ER and mitochondria and suggests that impaired ER-mitochondria association could contribute to the pathogenesis of PD.

scholarly journals Genetic deletion of trkB.T1 increases neuromuscular function

2012 ◽  
Vol 302 (1) ◽  
pp. C141-C153 ◽  
Author(s):  
Susan G. Dorsey ◽  
Richard M. Lovering ◽  
Cynthia L. Renn ◽  
Carmen C. Leitch ◽  
Xinyue Liu ◽  
...  
Keyword(s):  
Calcium Release ◽  
Contractile Activity ◽  
Muscle Tension ◽  
Neuromuscular Synapse ◽  
Neuromuscular Function ◽  
In Vitro Assays ◽  
Tyrosine Kinase Receptor ◽  
Akt Activation

Neurotrophin-dependent activation of the tyrosine kinase receptor trkB.FL modulates neuromuscular synapse maintenance and function; however, it is unclear what role the alternative splice variant, truncated trkB ( trkB.T1), may have in the peripheral neuromuscular axis. We examined this question in trkB.T1 null mice and demonstrate that in vivo neuromuscular performance and nerve-evoked muscle tension are significantly increased. In vitro assays indicated that the gain-in-function in trkB.T1 −/− animals resulted specifically from an increased muscle contractility, and increased electrically evoked calcium release. In the trkB.T1 null muscle, we identified an increase in Akt activation in resting muscle as well as a significant increase in trkB.FL and Akt activation in response to contractile activity. On the basis of these findings, we conclude that the trkB signaling pathway might represent a novel target for intervention across diseases characterized by deficits in neuromuscular function.

scholarly journals Calcium channel ITPR2 and mitochondria–ER contacts promote cellular senescence and aging

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dorian V. Ziegler ◽  
David Vindrieux ◽  
Delphine Goehrig ◽  
Sara Jaber ◽  
Guillaume Collin ◽  
...  
Keyword(s):  
Cellular Senescence ◽  
Calcium Release ◽  
Liver Steatosis ◽  
Metabolic Stress ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Age Related ◽  
Trisphosphate Receptor

AbstractCellular senescence is induced by stresses and results in a stable proliferation arrest accompanied by a pro-inflammatory secretome. Senescent cells accumulate during aging, promoting various age-related pathologies and limiting lifespan. The endoplasmic reticulum (ER) inositol 1,4,5-trisphosphate receptor, type 2 (ITPR2) calcium-release channel and calcium fluxes from the ER to the mitochondria are drivers of senescence in human cells. Here we show that Itpr2 knockout (KO) mice display improved aging such as increased lifespan, a better response to metabolic stress, less immunosenescence, as well as less liver steatosis and fibrosis. Cellular senescence, which is known to promote these alterations, is decreased in Itpr2 KO mice and Itpr2 KO embryo-derived cells. Interestingly, ablation of ITPR2 in vivo and in vitro decreases the number of contacts between the mitochondria and the ER and their forced contacts induce premature senescence. These findings shed light on the role of contacts and facilitated exchanges between the ER and the mitochondria through ITPR2 in regulating senescence and aging.

Structural characterization of amorphous calcium carbonate-binding protein: an insight into the mechanism of amorphous calcium carbonate formation

2013 ◽  
Vol 453 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Jingtan Su ◽  
Xiao Liang ◽  
Qiang Zhou ◽  
Guiyou Zhang ◽  
Hongzhong Wang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Binding Sites ◽  
Binding Protein ◽  
Homology Modelling ◽  
Size Exclusion ◽  
Structural Basis ◽  
Amorphous Calcium Carbonate ◽  
Carbonate Formation

ACC (amorphous calcium carbonate) plays an important role in biomineralization process for its function as a precursor for calcium carbonate biominerals. However, it is unclear how biomacromolecules regulate the formation of ACC precursor in vivo. In the present study, we used biochemical experiments coupled with bioinformatics approaches to explore the mechanisms of ACC formation controlled by ACCBP (ACC-binding protein). Size-exclusion chromatography, chemical cross-linking experiments and negative staining electron microscopy reveal that ACCBP is a decamer composed of two adjacent pentamers. Sequence analyses and fluorescence quenching results indicate that ACCBP contains two Ca2+-binding sites. The results of in vitro crystallization experiments suggest that one Ca2+-binding site is critical for ACC formation and the other site affects the ACC induction efficiency. Homology modelling demonstrates that the Ca2+-binding sites of pentameric ACCBP are arranged in a 5-fold symmetry, which is the structural basis for ACC formation. To the best of our knowledge, this is the first report on the structural basis for protein-induced ACC formation and it will significantly improve our understanding of the amorphous precursor pathway.

scholarly journals A comparison between the combined effect of calcium carbonate with sucroferric oxyhydroxide and other phosphate binders: an in vitro and in vivo experimental study

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Atsushi Yaguchi ◽  
Kenji Akahane ◽  
Kumi Tsuchioka ◽  
Saori Yonekubo ◽  
Shota Yamamoto ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Lanthanum Carbonate ◽  
Combined Effect ◽  
Ferric Citrate ◽  
Phosphate Binders ◽  
Phosphate Solution ◽  
Phosphate Binding ◽  
Sevelamer Hydrochloride

Abstract Background Approximately 30% of patients on dialysis received combination therapy for their phosphate binder prescription; however, few studies for combined effects of phosphate binders are reported. For the purpose of evaluating the efficacy of combination therapy, we compared the efficacy of sucroferric oxyhydroxide (PA21) combined with calcium carbonate with that of lanthanum carbonate hydrate, sevelamer hydrochloride, and ferric citrate hydrate combined with calcium carbonate. Methods For in vitro studies, calcium carbonate and the other phosphate binders alone or in combination were stirred in phosphate solution at pH 2–8 for 2 h. After centrifuging the suspension, the phosphorus level in the supernatant was determined. For in vivo studies, rats were orally administered calcium carbonate and the other phosphate binders (except for sevelamer hydrochloride) alone or in combination, followed by oral administration of phosphate solution adjusted to pH 2 or 7. Serum samples were collected from the rats at predetermined timepoints and the serum phosphorus levels were determined and analyzed using a two-way analysis of variance. Results In the in vitro study, the measured phosphate-binding capacity of combining sevelamer hydrochloride, PA21, and lanthanum carbonate hydrate with calcium carbonate was approximately equal to or greater than the theoretical values under most conditions. Furthermore, these combined effects were insensitive to pH in that order. The measured phosphate-binding capacity of ferric citrate hydrate combined with calcium carbonate was smaller than the theoretical values, and the combination did not exhibit efficacy under any of the tested conditions. In the in vivo study, the combined effect of PA21 and calcium carbonate at both pH values and that of lanthanum carbonate hydrate and calcium carbonate at pH 2 were additive. In contrast, the combined effect of lanthanum carbonate hydrate and calcium carbonate at pH 7 and that of ferric citrate hydrate and calcium carbonate at pH 2 were antagonistic. Conclusions These results suggest that coadministration of PA21 and calcium carbonate showed good and relatively stable efficacy throughout the range of the gastrointestinal pH and that combining lanthanum carbonate hydrate and ferric citrate hydrate with calcium carbonate may not produce the expected efficacy under certain conditions.

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