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.

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.

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.

Novel SLC12A3 mutation in Gitelman syndrome

2021 ◽  
Vol 14 (1) ◽  
pp. e238097
Author(s):  
Rita Veríssimo ◽  
Luís Leite de Sousa ◽  
Tiago J Carvalho ◽  
Pedro Fidalgo
Keyword(s):  
Metabolic Alkalosis ◽  
Autosomal Recessive ◽  
Novel Mutation ◽  
Gene Mutations ◽  
Urinary Calcium ◽  
Gitelman Syndrome ◽  
Renal Ultrasound ◽  
Calcium Excretion ◽  
Slc12a3 Gene ◽  
Specific Symptoms

Gitelman syndrome (GS) is an autosomal recessive disease characterised by the presence of hypokalaemic metabolic alkalosis with hypomagnesaemia and hypocalciuria. The prevalence of this disease is 1–10/40 000. GS is usually associated with mild and non-specific symptoms and many patients are only diagnosed in adulthood. The disease is caused by mutations in the SLC12A3 gene. We present the case of a 49-year-old man referred to a nephrology appointment due to persistent hypokalaemia and hypomagnesaemia. Complementary evaluation revealed hypokalaemia, hypomagnesaemia, metabolic alkalosis, hyperreninaemia, increased chloride and sodium urinary excretion, and reduced urinary calcium excretion. Renal function, remainder serum and urinary ionogram, and renal ultrasound were normal. A diagnosis of GS was established and confirmed with genetic testing which revealed a novel mutation in SLC12A3 (c.1072del, p.(Ala358Profs*12)). This novel mutation extends the spectrum of known SLC12A3 gene mutations and further supports the allelic heterogeneity of GS.

Regulation of COX-2 Mediates Acid-Induced Bone Calcium Efflux in Vitro

2007 ◽  
Vol 22 (6) ◽  
pp. 907-917 ◽  
Author(s):  
Nancy S Krieger ◽  
Kevin K Frick ◽  
Kelly LaPlante Strutz ◽  
Anne Michalenka ◽  
David A Bushinsky
Keyword(s):  
Calcium Efflux ◽  
Bone Calcium ◽  
Cox 2

Additive effects of acidosis and parathyroid hormone on mouse osteoblastic and osteoclastic function

1995 ◽  
Vol 269 (6) ◽  
pp. C1364-C1370 ◽  
Author(s):  
D. A. Bushinsky ◽  
E. L. Nilsson
Keyword(s):  
Parathyroid Hormone ◽  
Collagen Synthesis ◽  
Cell Function ◽  
Inverse Correlation ◽  
Bone Cell ◽  
Additive Effects ◽  
Calcium Efflux ◽  
Glucuronidase Activity ◽  
Stage Renal Disease ◽  
End Stage

Patients with end-stage renal disease are acidotic and often develop secondary hyperparathyroidism. Whether acidosis contributes to the bone disease observed in these patients is not clear. To determine whether acidosis and parathyroid hormone (PTH) have additive effects on net calcium efflux (JCa+) from bone and on bone cell function, we measured JCa+, osteoblastic collagen synthesis, and osteoclastic beta-glucuronidase release from neonatal mouse calvariae cultured in control (Ctl, pH approximately 7.4) or acidified (Met, pH approximately 7.1) medium with or without a submaximal concentration of PTH (10(-10) M) for 48 h. Compared with Ctl, from 24 to 48 h JCa+ was increased with Met and with PTH, and the combination of Met + PTH increased JCa+ further. Compared with Ctl, collagen synthesis was decreased with Met and with PTH and decreased further with Met + PTH. There was an inverse correlation between percent collagen synthesis and JCa+. Compared with Ctl, beta-glucuronidase release into the medium was increased with Met and with PTH and increased further with Met + PTH. There was a direct correlation between medium beta-glucuronidase activity and JCa+. Osteoclastic beta-glucuronidase activity correlated inversely with osteoblastic collagen synthesis. During cultures to 96 h, there continued to be greater JCa+ from calvariae incubated with Met + PTH than from those with either treatment alone. Thus acidosis and PTH independently stimulated JCa+ from bone, inhibited osteoblastic collagen synthesis, and stimulated osteoclastic beta-glucuronidase secretion, whereas the combination had a greater effect on each of these parameters than either treatment alone. These findings indicate that acidosis and PTH can have an additive effect on bone cell function and suggest that uremic osteodystrophy may result from a combination of a low pH and an elevated PTH.

Stimulated osteoclastic and suppressed osteoblastic activity in metabolic but not respiratory acidosis

1995 ◽  
Vol 268 (1) ◽  
pp. C80-C88 ◽  
Author(s):  
D. A. Bushinsky
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Collagen Synthesis ◽  
Cell Function ◽  
Respiratory Acidosis ◽  
Bone Cell ◽  
Calcium Efflux ◽  
Osteoblastic Activity ◽  
Glucuronidase Activity

When bone is cultured in acidic medium produced by a reduced bicarbonate concentration ([HCO(3-)]), a model of metabolic acidosis, there is greater net calcium efflux than when the same decrement in pH is produced by an increased partial pressure of carbon dioxide (PCO2), a model of respiratory acidosis. To determine the effects of metabolic and respiratory acidosis on bone cell function we cultured neonatal mouse calvariae for 48 h under control conditions (pH approximately 7.40, PCO2 approximately 41 mmHg, [HCO(3-)] approximately 25 meq/l) or under isohydric acidic conditions simulating metabolic (pH approximately 7.09, [HCO(3-)] approximately 12) or respiratory (pH approximately 7.10, PCO2 approximately 86) acidosis and measured osteoblastic collagen synthesis and alkaline phosphatase activity and osteoclastic beta-glucuronidase activity. Collagen synthesis was inhibited by metabolic (23.2 +/- 1.3 vs. 30.3 +/- 1.0% in control) but was not altered by respiratory (32.3 +/- 0.6) acidosis. Alkaline phosphatase activity was inhibited by metabolic (402 +/- 16 vs. 471 +/- 15 nmol P.min-1.mg protein-1 in control) but not altered by respiratory (437 +/- 25) acidosis. beta-Glucuronidase activity was stimulated by metabolic (1.02 +/- 0.06 vs. 0.78 +/- 0.05 micrograms phenolphthalein released.bone-1.h-1 in control) but not altered by respiratory (0.73 +/- 0.06) acidosis. Net calcium efflux in control was increased by metabolic (783 +/- 57 vs. 20 +/- 57 nmol.bone-1.48 h-1 in control) and by respiratory (213 +/- 45) acidosis; however, calcium efflux with metabolic was greater than with respiratory acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Calcilytic Agent NPS 2143 Rectifies Hypocalcemia in a Mouse Model With an Activating Calcium-Sensing Receptor (CaSR) Mutation: Relevance to Autosomal Dominant Hypocalcemia Type 1 (ADH1)

Endocrinology ◽  
2015 ◽  
Vol 156 (9) ◽  
pp. 3114-3121 ◽  
Author(s):  
Fadil M. Hannan ◽  
Gerard V. Walls ◽  
Valerie N. Babinsky ◽  
M. Andrew Nesbit ◽  
Enikö Kallay ◽  
...  
Keyword(s):  
Mouse Model ◽  
Urinary Calcium ◽  
Hek293 Cells ◽  
Calcium Excretion ◽  
Wild Type ◽  
Calcium Sensing Receptor ◽  
Gain Of Function ◽  
Calcium Sensing

Autosomal dominant hypocalcemia type 1 (ADH1) is caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR) and may lead to symptomatic hypocalcemia, inappropriately low serum PTH concentrations and hypercalciuria. Negative allosteric CaSR modulators, known as calcilytics, have been shown to normalize the gain-of-function associated with ADH-causing CaSR mutations in vitro and represent a potential targeted therapy for ADH1. However, the effectiveness of calcilytic drugs for the treatment of ADH1-associated hypocalcemia remains to be established. We have investigated NPS 2143, a calcilytic compound, for the treatment of ADH1 by in vitro and in vivo studies involving a mouse model, known as Nuf, which harbors a gain-of-function CaSR mutation, Leu723Gln. Wild-type (Leu723) and Nuf mutant (Gln723) CaSRs were expressed in HEK293 cells, and the effect of NPS 2143 on their intracellular calcium responses was determined by flow cytometry. NPS 2143 was also administered as a single ip bolus to wild-type and Nuf mice and plasma concentrations of calcium and PTH, and urinary calcium excretion measured. In vitro administration of NPS 2143 decreased the intracellular calcium responses of HEK293 cells expressing the mutant Gln723 CaSR in a dose-dependent manner, thereby rectifying the gain-of-function associated with the Nuf mouse CaSR mutation. Intraperitoneal injection of NPS 2143 in Nuf mice led to significant increases in plasma calcium and PTH without elevating urinary calcium excretion. These studies of a mouse model with an activating CaSR mutation demonstrate NPS 2143 to normalize the gain-of-function causing ADH1 and improve the hypocalcemia associated with this disorder.

MO1004IMBALANCE IN URINARY PROTEOGLYCANS AND THE INSULIN GROWTH FACTOR (IGF) AXIS IN CHILDREN WITH NEPHROLITHIASIS*

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Larisa Kovacevic ◽  
Natalija Kovacevic ◽  
Yegappan Lakshmanan
Keyword(s):  
Growth Factor ◽  
Urinary Calcium ◽  
P Value ◽  
Calcium Excretion ◽  
Exact Test ◽  
Insulin Growth Factor ◽  
Ecm Proteins ◽  
Proteomic Approach ◽  
Elisa Testing

Abstract Background and Aims In vitro experiments have shown that exposure of renal epithelial cells to calcium oxalate crystals leads to synthesis of proteins involved in extracellular matrix (ECM) production. Cell proliferation and accumulation of ECM proteins have been reported in animal models and kidney biopsies from patients with stones. Based on the role of ECM in the Randall plaque formation, we aimed to identify and quantify ECM proteins in the urine of children with nephrolithiasis (RS) using a proteomic approach. Method Prospective, controlled, pilot study of pooled urine from RS (N=30, 24 females, mean age 12.95±4.03 years) versus age- and gender-matched healthy controls (HC), using liquid chromatography-mass spectrometry (LC-MS/MS). Patient inclusion criteria consisted of age 5-18 years, history of clinically (typical renal colic) and radiographically (ultrasound or CT) proven renal stone, at least two 24-hour satisfactory urine collections (urinary creatinine more than 15 mg/kg/day), absence of hematuria or pyuria, and normal renal function. Children who were not toilet trained, or those with bladder stones, nephrocalcinosis, neuropathic bladder, major congenital bladder abnormality, active urinary tract infection, presence of blood in urine, chronic kidney disease, previous major reconstructive bladder surgery requiring catheterization, and significant cardiac, pulmonary, gastro-intestinal, and neurological problems were excluded. Relative protein abundance was estimated using spectral counting. The criteria for protein selection were: 1) patient/control abundance ratios of >5 or <0.2 as a threshold to be well above observed technical variations in MS experiments; and 2) ≤0.05 p-value for the Fisher’s Exact Test. Results were confirmed by ELISA testing. Statistical analyses were conducted with IBM SPSS® version 20. Results We found 36 (15.7%) ECM proteins out of 229 proteins that met the above criteria. Significant differences between RS and HC were found among two proteoglycans and four insulin growth factor (IGF) proteins (Table). Significant increase in the urinary excretion of IGFBP4 in RS (37.00 ± 37.68 ng/mg creatinine ) versus HC (19.04 ± 20.32 ng/mg creatinine) was confirmed by ELISA (p=0.049). Statistically significant correlation was found between urinary IGFBP4 concentration and 24-hour urinary calcium excretion (p<0.001). Conclusion Alteration in proteoglycans and the IGF axis appears to have a significant role in the mechanism of nephrolithiasis, likely by modulating ECM biosynthesis. Further understanding of their roles in nephrolithiasis may aid in generation of novel therapeutic approaches.  

Cellular contribution to pH-mediated calcium flux in neonatal mouse calvariae

1985 ◽  
Vol 248 (6) ◽  
pp. F785-F789 ◽  
Author(s):  
D. A. Bushinsky ◽  
J. M. Goldring ◽  
F. L. Coe
Keyword(s):  
Sodium Azide ◽  
Culture Medium ◽  
Cell Function ◽  
Bone Cell ◽  
Neonatal Mouse ◽  
Calcium Flux ◽  
Calcium Efflux ◽  
Medium Ph ◽  
Freeze Thaw ◽  
Net Flux

Net calcium flux from cultured neonatal mouse calvariae into the culture medium is pH dependent, and acidified culture medium causes egress of calcium from bone. To determine whether calcium flux is mediated by pH effects on bone cell function, we cultured calvariae for 24 h with sodium azide, acetazolamide, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], or after three successive freeze-thaw cycles, treatments that would be expected to alter bone cell function. We recultured bones for 3 h with the respective treatment and measured calcium flux. Sodium azide and freeze-thaw cycles produced a net influx of calcium (JCa = -22 +/- 7 and -23 +/- 6 nmol X bone-1 X 3 h-1, respectively) compared with net efflux of control bones (JCa = 35 +/- 6) at a similar initial medium pH. Acetazolamide reduced net flux to 0 (JCa = 7 +/- 6). PTH and 1,25(OH)2D3 increased net calcium efflux from bone (JCa = 78 +/- 7 and 74 +/- 10, respectively). Despite changing net flux, the slope dependence of net flux on medium pH was the same in the control group and all five treated groups of bones. The similarity of slopes indicates that the pH dependence of net flux is not a result of pH acting on bone cells but probably an effect of altered mineral equilibria. The difference in net flux at similar pH indicates that calcium efflux is partially inhibited by acetazolamide and stimulated by both PTH and 1,25(OH)2D3.

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