1
|
Yang Y, Tseng WJ, Wang B. Abaloparatide Maintains Normal Rat Blood Calcium Level in Part Via 1,25-Dihydroxyvitamin D/osteocalcin Signaling Pathway. Endocrinology 2023; 164:bqad117. [PMID: 37493045 PMCID: PMC10424883 DOI: 10.1210/endocr/bqad117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/01/2023] [Accepted: 07/25/2023] [Indexed: 07/27/2023]
Abstract
The PTH-related peptide(1-34) analog, abaloparatide (ABL), is the second anabolic drug available for the treatment of osteoporosis. Previous research demonstrated that ABL had a potent anabolic effect but caused hypercalcemia at a significantly lower rate. However, the mechanism by which ABL maintains the stability of blood calcium levels remains poorly understood. Our in vivo data showed that ABL treatment (40 µg/kg/day for 7 days) significantly increased rat blood level of 1,25-dihydroxyvitamin D [1,25-(OH)2D] without raising the blood calcium value. ABL also significantly augmented the carboxylated osteocalcin (Gla-Ocn) in the blood and bone that is synthesized by osteoblasts, and increased noncarboxylated Ocn, which is released from the bone matrix to the circulation because of osteoclast activation. The in vitro data showed that ABL (10 nM for 24 hours) had little direct effects on 1,25-(OH)2D synthesis and Gla-Ocn formation in nonrenal cells (rat osteoblast-like cells). However, ABL significantly promoted both 1,25-(OH)2D and Gla-Ocn formation when 25-hydroxyvitamin D, the substrate of 1α-hydroxylase, was added to the cells. Thus, the increased 1,25-(OH)2D levels in rats treated by ABL result in high levels of Gla-Ocn and transient calcium increase in the circulation. Gla-Ocn then mediates calcium ions in the extracellular fluid at bone sites to bind to hydroxyapatite at bone surfaces. This regulation by Gla-Ocn at least, in part, maintains the stability of blood calcium levels during ABL treatment. We conclude that the signaling pathway of ABL/1,25-(OH)2D/Gla-Ocn contributes to calcium homeostasis and may help understand the mechanism of ABL for osteoporosis therapy.
Collapse
Affiliation(s)
- Yanmei Yang
- The Center for Translational Medicine, Departments of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Wei-Ju Tseng
- The Center for Translational Medicine, Departments of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Bin Wang
- The Center for Translational Medicine, Departments of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| |
Collapse
|
2
|
Roberts WE, Mangum JE, Schneider PM. Pathophysiology of Demineralization, Part I: Attrition, Erosion, Abfraction, and Noncarious Cervical Lesions. Curr Osteoporos Rep 2022; 20:90-105. [PMID: 35129809 PMCID: PMC8930910 DOI: 10.1007/s11914-022-00722-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/15/2021] [Indexed: 12/14/2022]
Abstract
PURPOSE OF THE REVIEW Compare pathophysiology for infectious and noninfectious demineralization disease relative to mineral maintenance, physiologic fluoride levels, and mechanical degradation. RECENT FINDINGS Environmental acidity, biomechanics, and intercrystalline percolation of endemic fluoride regulate resistance to demineralization relative to osteopenia, noncarious cervical lesions, and dental caries. Demineralization is the most prevalent chronic disease in the world: osteoporosis (OP) >10%, dental caries ~100%. OP is severely debilitating while caries is potentially fatal. Mineralized tissues have a common physiology: cell-mediated apposition, protein matrix, fluid logistics (blood, saliva), intercrystalline ion percolation, cyclic demineralization/remineralization, and acid-based degradation (microbes, clastic cells). Etiology of demineralization involves fluid percolation, metabolism, homeostasis, biomechanics, mechanical wear (attrition or abrasion), and biofilm-related infections. Bone mineral density measurement assesses skeletal mass. Attrition, abrasion, erosion, and abfraction are diagnosed visually, but invisible subsurface caries <400μm cannot be detected. Controlling demineralization at all levels is an important horizon for cost-effective wellness worldwide.
Collapse
Affiliation(s)
- W. Eugene Roberts
- grid.257413.60000 0001 2287 3919Indiana University & Purdue University at Indianapolis, 8260 Skipjack Drive, Indianapolis, IN 46236 USA
| | - Jonathan E. Mangum
- grid.1008.90000 0001 2179 088XDepartment of Biochemistry and Pharmacology, Dentistry and Health Sciences, University of Melbourne, Corner Grattan Street and Royal Parade, Parkville, Victoria 3010 Australia
| | - Paul M. Schneider
- grid.1008.90000 0001 2179 088XMelbourne Dental School, University of Melbourne, 720 Swanston St, Melbourne, Victoria 3010 Australia
| |
Collapse
|
3
|
Pirklbauer M, Fuchs L, Heiss R, Ratschiller T, Mayer G. Intradialytic Calcium Kinetics and Cardiovascular Disease in Chronic Hemodialysis Patients. Blood Purif 2020; 49:723-732. [PMID: 32712610 PMCID: PMC7677992 DOI: 10.1159/000508060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 04/20/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND/OBJECTIVE Calcium loading has been associated with cardiovascular risk in hemodialysis (HD) patients. However, it remains to be elucidated whether alterations of intradialytic calcium buffering add to the increased cardiovascular disease burden in this high-risk population. METHODS Intradialytic calcium kinetics was evaluated in a cross-sectional observational study by measuring dialysate-sided ionized calcium mass balance (iCaMB), calcium buffer capacity, and change in serum calcium levels in 40 chronic HD patients during a routine HD session. A dialysate calcium of 3.5 mEq/L was used to adequately challenge calcium buffer mechanisms. Aortic pulse wave velocity and serum osteocalcin levels were measured prior to the HD session. Presence of cardiovascular disease and diabetes was assessed. RESULTS The mean dialysate-sided iCaMB, extracellular fluid ionized calcium mass gain, and buffered ionized calcium mass were 469 (±154), 111 (±49), and 358 (±145) mg/HD, respectively. The mean ionized serum calcium increase (∆iCa) was 0.42 (±0.14) mEq/L per HD. The mean intradialytic calcium buffer capacity was 73 (±18)%. Multivariate regression analysis revealed significant independent association of (1) iCaMB with the dialysate-to-blood calcium gradient at HD start and (2) intradialytic calcium buffer capacity with undercarboxylated osteocalcin. The presence of coronary heart disease was associated with higher ∆iCa but not iCaMB in the multivariate model. CONCLUSIONS In line with our proof-of-concept study, we provide clinical evidence for a rapidly accessible and exchangeable calcium pool involved in intradialytic calcium regulation and for the role of osteocalcin as a potential biomarker. Our findings argue for evaluating the prognostic potential of intradialytic calcium kinetics in prospective clinical trials.
Collapse
Affiliation(s)
- Markus Pirklbauer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria,
| | - Lisa Fuchs
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Ramona Heiss
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Thomas Ratschiller
- Department of Cardiac, Vascular and Thoracic Surgery, Kepler University Hospital, Linz, Austria
| | - Gert Mayer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| |
Collapse
|
4
|
Dedic C, Hung TS, Shipley AM, Maeda A, Gardella T, Miller AL, Divieti Pajevic P, Kunkel JG, Rubinacci A. Calcium fluxes at the bone/plasma interface: Acute effects of parathyroid hormone (PTH) and targeted deletion of PTH/PTH-related peptide (PTHrP) receptor in the osteocytes. Bone 2018; 116:135-143. [PMID: 30053608 PMCID: PMC6158063 DOI: 10.1016/j.bone.2018.07.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/20/2018] [Accepted: 07/24/2018] [Indexed: 01/10/2023]
Abstract
Calcium ion concentration ([Ca2+]) in the systemic extracellular fluid, ECF-[Ca2+], is maintained around a genetically predetermined set-point, which combines the operational level of the kidney and bone/ECF interfaces. The ECF-[Ca2+] is maintained within a narrow oscillation range by the regulatory action of Parathyroid Hormone (PTH), Calcitonin, FGF-23, and 1,25(OH)2D3. This model implies two correction mechanisms, i.e. tubular Ca2+ reabsorption and osteoclast Ca2+ resorption. Although their alterations have an effect on the ECF-[Ca2+] maintenance, they cannot fully account for rapid correction of the continuing perturbations of plasma [Ca2+], which occur daily in life. The existence of Ca2+ fluxes at quiescent bone surfaces fulfills the role of a short-term error correction mechanism in Ca2+ homeostasis. To explore the hypothesis that PTH regulates the cell system responsible for the fast Ca2+ fluxes at the bone/ECF interface, we have performed direct real-time measurements of Ca2+ fluxes at the surface of ex-vivo metatarsal bones maintained in physiological conditions mimicking ECF, and exposed to PTH. To further characterize whether the PTH receptor on osteocytes is a critical component of the minute-to-minute ECF-[Ca2+] regulation, metatarsal bones from mice lacking the PTH receptor in these cells were tested ex vivo for rapid Ca2+ exchange. We performed direct real-time measurements of Ca2+ fluxes and concentration gradients by a scanning ion-selective electrode technique (SIET). To validate ex vivo measurements, we also evaluated acute calcemic response to PTH in vivo in mice lacking PTH receptors in osteocytes vs littermate controls. Our data demonstrated that Ca2+ fluxes at the bone-ECF interface in excised bones as well as acute calcemic response in the short-term were unaffected by PTH exposure and its signaling through its receptor in osteocytes. Rapid minute-to-minute regulation of the ECF-[Ca2+] was found to be independent of PTH actions on osteocytes. Similarly, mice lacking PTH receptor in osteocytes, responded to PTH challenge with similar calcemic increases.
Collapse
Affiliation(s)
- Christopher Dedic
- Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Tin Shing Hung
- Division of Life Sciences, State Key Laboratory for Molecular Neuroscience, HKUST, Hong Kong, China
| | | | - Akira Maeda
- Endocrine Unit, Massachusetts General Hospital, Boston, USA; Chugai Pharmaceutical, Japan
| | | | - Andrew L Miller
- Division of Life Sciences, State Key Laboratory for Molecular Neuroscience, HKUST, Hong Kong, China
| | - Paola Divieti Pajevic
- Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Joseph G Kunkel
- Pickus Center for Biomedical Research, University of New England, Biddeford, ME, USA
| | - Alessandro Rubinacci
- Bone Metabolism Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milano, Italy.
| |
Collapse
|
5
|
Hohman EE, Hodges JK, Wastney ME, Lachcik PJ, Han CY, Dwyer D, Peacock M, Kostenuik PJ, Weaver CM. Serum calcium concentration is maintained when bone resorption is suppressed by osteoprotegerin in young growing male rats. Bone 2018; 116:162-170. [PMID: 30077758 DOI: 10.1016/j.bone.2018.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 07/26/2018] [Accepted: 08/01/2018] [Indexed: 01/22/2023]
Abstract
Serum calcium (Ca) is maintained in a narrow range through regulation of Ca metabolism in the intestine, kidney, and bone. Calcium is incorporated and resorbed from bone during bone remodeling via cellular processes as well as by exchange. Both routes contribute to calcium homeostasis. To assess the magnitude of bone turnover contribution to calcium homeostasis we labeled bone with a Ca tracer and measured Ca release following stimulation or suppression of bone resorption. Young growing male rats (n = 162) were dosed with 45Ca to label skeletal Ca. After a one-month period to allow the label to incorporate into the skeleton, rats were treated with a bone resorption antagonist (OPG), a bone resorption agonist (RANKL), or vehicle control (PBS). Serum and urine 45Ca and total Ca, and serum TRACP5b (a bone resorption biomarker), were monitored for 45 days following treatment. Tracer data were analyzed by a compartmental model using WinSAAM to quantify dynamic changes in Ca metabolism and identify sites of change following treatment. In RANKL treated rats, both serum 45Ca and serum TRACP5b were increased by >70% due to a 25-fold increase in bone resorption. In OPG treated rats, both serum 45Ca and serum TRACP5b were suppressed by >70% due to a 75% decrease in bone resorption, a 3-fold increase in bone formation, and a 50% increase in absorption. Because TRACP5b and 45Ca responded similarly, we conclude that Ca release from bone into serum occurs mostly via osteoclast-mediated bone resorption. However, because serum Ca concentration did not change with altered resorption in response to either RANKL or OPG treatment, we also conclude that serum Ca concentration under normal dietary conditions in young growing male rats is maintained by processes in addition to cellular bone resorption.
Collapse
Affiliation(s)
- Emily E Hohman
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Joanna K Hodges
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Meryl E Wastney
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Pamela J Lachcik
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Chun-Ya Han
- Metabolic Disorders Research, Amgen, Thousand Oaks, CA, USA
| | - Denise Dwyer
- Metabolic Disorders Research, Amgen, Thousand Oaks, CA, USA
| | - Munro Peacock
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Paul J Kostenuik
- Phylon Pharma Services, Newbury Park, CA, USA; University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Connie M Weaver
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA.
| |
Collapse
|
6
|
Pirklbauer M, Schupart R, Mayer G. Acute calcium kinetics in haemodialysis patients. Eur J Clin Invest 2016; 46:976-984. [PMID: 27689678 DOI: 10.1111/eci.12680] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 09/27/2016] [Indexed: 12/21/2022]
Abstract
INTRODUCTION To avoid excessive calcium loading in haemodialysis (HD) patients, current guidelines suggest a dialysate calcium concentration (dCa) of 2·5 mEq/L based on relatively stable intradialytic serum calcium levels. However, the latter do not account for possible calcium storage in acutely accessible pools. A rapidly exchangeable calcium pool located at the bone level has been previously proposed to be involved in acute (minute-to-minute) extracellular calcium regulation. DESIGN To evaluate the contribution of this pool in the maintenance of serum calcium levels, acute calcium buffer capacity was assessed by measuring intradialytic dialysate-sided ionized calcium mass balance (iCaMB ) and change in extracellular fluid calcium mass in chronic HD patients using a dCa of 3·5 (n = 28) and 2·5 (n = 10) mEq/L. Serum osteocalcin, the most abundant noncollagenous bone protein, was measured before the HD session. RESULTS iCaMB was invariably positive for both 2·5 and 3·5 mEq/L dCa, with a mean of 434 (±125) and 725 (±162) mg/HD, respectively (P < 0·001). Buffered intradialytic calcium load was 410 (±116) and 565 (±130) mg/HD, and acute calcium buffer capacity was 95 (±8)% and 78 (±7)% (mean values at 2·5 and 3·5 mEq/L dCa, respectively) (P < 0·001). Using 3·5 mEq/L dCa, an independent association of acute calcium buffer capacity with undercarboxylated osteocalcin (β = 0·512, P = 0·002) was demonstrated. CONCLUSIONS Our data strongly suggest the existence of a rapidly exchangeable calcium pool that counteracts acute serum calcium deviations in HD patients. This study provides, for the first time, experimental evidence for the involvement of bone in acute extracellular calcium regulation in vivo.
Collapse
Affiliation(s)
- Markus Pirklbauer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Ramona Schupart
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Gert Mayer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| |
Collapse
|
7
|
Cosso R, Falchetti A. Vitamin K and bone metabolism: the myth and the truth. EXPERT REVIEW OF PRECISION MEDICINE AND DRUG DEVELOPMENT 2016. [DOI: 10.1080/23808993.2016.1174061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
8
|
Duan XQ, Li YH, Zhang XY, Zhao ZT, Wang Y, Wang H, Li GS, Jing L. Mechanisms of Intracellular Calcium Homeostasis in MC3T3-E1 Cells and Bone Tissues of Sprague-Dawley Rats Exposed to Fluoride. Biol Trace Elem Res 2016; 170:331-9. [PMID: 26276564 DOI: 10.1007/s12011-015-0465-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 07/29/2015] [Indexed: 10/23/2022]
Abstract
Calcium homeostasis of osteoblasts (OBs) has an important role in the physiology and pathology of bone tissue. In order to study the mechanisms of intracellular calcium homeostasis, MC3T3-E1 cells and Sprague-Dawley rats were treated with different concentrations of fluoride. Then, we examined intracellular-free calcium ion ([Ca(2+)]i) in MC3T3-E1 cells as well as mRNA and protein levels of Cav1.2, the main subunit of L-type voltage-dependent calcium channels (VDCCs), Na(+)/Ca(2+) exchange carriers (NCS), and plasma membrane Ca(2+)-ATPase (PMCA), inositol 1,4,5-trisphosphate receptor (IP3R) channels, sarco/endoplasmic reticulum calcium ATPase 2b (SERCA2b)/ATP2A2 in vitro, and rat bone tissues in vivo. Our results showed that [Ca(2+)]i of fluoride-treated OBs increased in a concentration-dependent manner with an increase in the concentration of fluoride. We also found that the low dose of fluoride led to high expression levels of Cav1.2, NCS-1, and PMCA and low expression levels of IP3R and SERCA2b/ATP2A2, while the high dose of fluoride induced an increase in SERCA2b/ATP2A2 levels and decrease in Cav1.2, PMCA, NCS-1, and IP3R levels. These results demonstrate that calcium channels and calcium pumps of plasma and endoplasmic reticulum (ER) membranes keep intracellular calcium homeostasis by regulating Cav1.2, NCS-1, PMCA, IP3R, and SERCA2b/ATP2A2 expression.
Collapse
Affiliation(s)
- Xiao-qin Duan
- The Second Hospital Norman Bethune of Jilin University, Changchun, 130041, People's Republic of China
| | - Yan-hui Li
- The Second Hospital Norman Bethune of Jilin University, Changchun, 130041, People's Republic of China
| | - Xiu-yun Zhang
- Institute of Endemic Disease of Jilin University, 1163 Xinmin Street, Changchun, 130021, People's Republic of China
| | - Zhi-tao Zhao
- Institute of Endemic Disease of Jilin University, 1163 Xinmin Street, Changchun, 130021, People's Republic of China
| | - Ying Wang
- The First Hospital Norman Bethune of Jilin University, Changchun, 130021, People's Republic of China
| | - Huan Wang
- The Second Hospital Norman Bethune of Jilin University, Changchun, 130041, People's Republic of China
| | - Guang-sheng Li
- Institute of Endemic Disease of Jilin University, 1163 Xinmin Street, Changchun, 130021, People's Republic of China
| | - Ling Jing
- Institute of Endemic Disease of Jilin University, 1163 Xinmin Street, Changchun, 130021, People's Republic of China.
| |
Collapse
|
9
|
Duan XQ, Zhao ZT, Zhang XY, Wang Y, Wang H, Liu DW, Li GS, Jing L. Fluoride affects calcium homeostasis and osteogenic transcription factor expressions through L-type calcium channels in osteoblast cell line. Biol Trace Elem Res 2014; 162:219-26. [PMID: 25201340 DOI: 10.1007/s12011-014-0118-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 08/28/2014] [Indexed: 01/22/2023]
Abstract
Osteoblast L-type voltage-dependent calcium channels (VDCC) play important roles in maintaining intracellular homeostasis and influencing multiple cellular processes. In particular, they contribute to the activities and functions of osteoblasts (OBs). In order to study how L-type VDCC modulate calcium ion (Ca(2+)) homeostasis and the expression of osteogenic transcription factors in OBs exposed to fluoride, MC3T3-E1 cells were exposed to a gradient of concentrations of fluoride (0, 2.0, 5.0, 10.0 mg/L) in combination with 10 μM nifedipine, a specific inhibitor of VDCC, for 48 h. We examined messenger RNA (mRNA) and protein levels of Cav1.2, the main subunit of VDCC, and c-fos, c-jun, runt-related transcription factor 2 (Runx2), osterix (OSX), and intracellular free Ca(2+) ([Ca(2+)]i) concentrations in MC3T3-E1 cells. Our results showed that [Ca(2+)]i levels increased in a dose-dependent manner with increase in concentration of fluoride. Meantime, results indicated that lower concentrations of fluoride (less than 5 mg/L, especially 2 mg/L) can lead to high expression of Cav1.2 and enhance osteogenic function, while high concentration of fluoride (10 mg/L) can induce decreased Cav1.2 and osteogenic transcriptional factors in MC3T3E1 cells exposed to fluoride. However, the levels of [Ca(2+)]i, Cav1.2, c-fos, c-jun, Runx2, and OSX induced by fluoride were significantly altered and even reversed in the presence of nifedipine. These results demonstrate that L-type calcium channels play a crucial role in Ca(2+) homeostasis and they affect the expression of osteogenic transcription factors in fluoride-treated osteoblasts.
Collapse
Affiliation(s)
- Xiao-Qin Duan
- Department of Rehabilitation Medicine of the Second Hospital Norman Bethune, JiLin University, Changchun, 130041, People's Republic of China
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Martelli D, Luppi M, Cerri M, Tupone D, Perez E, Zamboni G, Amici R. Waking and sleeping following water deprivation in the rat. PLoS One 2012; 7:e46116. [PMID: 23029406 PMCID: PMC3454381 DOI: 10.1371/journal.pone.0046116] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 08/28/2012] [Indexed: 11/30/2022] Open
Abstract
Wake-sleep (W-S) states are affected by thermoregulation. In particular, REM sleep (REMS) is reduced in homeotherms under a thermal load, due to an impairment of hypothalamic regulation of body temperature. The aim of this work was to assess whether osmoregulation, which is regulated at a hypothalamic level, but, unlike thermoregulation, is maintained across the different W-S states, could influence W-S occurrence. Sprague-Dawley rats, kept at an ambient temperature of 24°C and under a 12 h∶12 h light-dark cycle, were exposed to a prolonged osmotic challenge of three days of water deprivation (WD) and two days of recovery in which free access to water was restored. Two sets of parameters were determined in order to assess: i) the maintenance of osmotic homeostasis (water and food consumption; changes in body weight and fluid composition); ii) the effects of the osmotic challenge on behavioral states (hypothalamic temperature (Thy), motor activity, and W-S states). The first set of parameters changed in WD as expected and control levels were restored on the second day of recovery, with the exception of urinary Ca++ that almost disappeared in WD, and increased to a high level in recovery. As far as the second set is concerned, WD was characterized by the maintenance of the daily oscillation of Thy and by a decrease in activity during the dark periods. Changes in W-S states were small and mainly confined to the dark period: i) REMS slightly decreased at the end of WD and increased in recovery; ii) non-REM sleep (NREMS) increased in both WD and recovery, but EEG delta power, a sign of NREMS intensity, decreased in WD and increased in recovery. Our data suggest that osmoregulation interferes with the regulation of W-S states to a much lesser extent than thermoregulation.
Collapse
Affiliation(s)
- Davide Martelli
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
- Systems Neurophysiology Division, Florey Neuroscience Institutes, University of Melbourne, Melbourne, Australia
| | - Marco Luppi
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
| | - Matteo Cerri
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
| | - Domenico Tupone
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
- Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Emanuele Perez
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
| | - Giovanni Zamboni
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
- * E-mail:
| | - Roberto Amici
- Department of Human and General Physiology, Alma Mater Studiorum-University of Bologna, Bologna, Italy
| |
Collapse
|
11
|
Pirklbauer M, Mayer G. The exchangeable calcium pool: physiology and pathophysiology in chronic kidney disease. Nephrol Dial Transplant 2011; 26:2438-44. [PMID: 21551087 DOI: 10.1093/ndt/gfr207] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Excessive soft tissue and vascular calcifications are typical complications of chronic kidney disease (CKD) and disorders of phosphate homeostasis are considered to be a major contributor to the pathogenesis. However, at least in some individuals, calcium administration also increases the risk, and furthermore, it is widely accepted that there is a link between bone disease and vascular pathology. In this review, we discuss the role of the bone exchangeable calcium pool (ECP) in the acute regulation of the serum calcium concentration (Ca(s)) in health and CKD. This pool is able to buffer an acute calcium load as well as to maintain a stable Ca(s) during acute calcium deprivation. Indeed, the minute-to-minute regulation of Ca(s) appears to depend exclusively on this mechanism without any obvious contribution of other factors like parathyroid hormone, which nonetheless define the Ca(s) steady state set point. It is tempting to speculate that a reduction of the bone ECP plasticity in some patients with CKD leads to short-lasting increases in Ca(s) above the individual mid- to long-term set point as observed during haemodialysis or after the ingestion of calcium-containing phosphate binders. This could contribute to and partially explain the propensity of these subjects to develop extraosseous calcifications. An improved understanding of the processes involved and the availability of new techniques to assess the capacity of this pool, at least in dialysis patients, will make this area an attractive target for new investigations.
Collapse
Affiliation(s)
- Markus Pirklbauer
- Department of Internal Medicine IV, Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | | |
Collapse
|
12
|
Rubinacci A. Expanding the functional spectrum of vitamin K in bone. Focus on: “Vitamin K promotes mineralization, osteoblast to osteocyte transition, and an anti-catabolic phenotype by γ-carboxylation-dependent and -independent mechanisms”. Am J Physiol Cell Physiol 2009; 297:C1336-8. [DOI: 10.1152/ajpcell.00452.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|