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Bruton J, Cheng AJ, Westerblad H. Measuring Ca 2+ in Living Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:7-26. [PMID: 31646505 DOI: 10.1007/978-3-030-12457-1_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Measuring free Ca2+ concentration ([Ca2+]) in the cytosol or organelles is routine in many fields of research. The availability of membrane permeant forms of indicators coupled with the relative ease of transfecting cell lines with biological Ca2+ sensors have led to the situation where cellular and subcellular [Ca2+] is examined by many non-specialists. In this chapter, we evaluate the most used Ca2+ indicators and highlight what their major advantages and disadvantages are. We stress the potential pitfalls of non-ratiometric techniques for measuring Ca2+ and the clear advantages of ratiometric methods. Likely improvements and new directions for Ca2+ measurement are discussed.
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Affiliation(s)
- Joseph Bruton
- Department of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden.
| | - Arthur J Cheng
- Department of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Håkan Westerblad
- Department of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Wang Y, Hu YC, Zhou Y, Zhao L, Chen D, Li LL, Jiang L, Zhang ZC, Li SN, Wen SN, Ruan YF, Liu N, Qiao Y, Lv Q, Hu R, Du X, Liu XH, Ma CS, Dong JZ, Bai R. Relationship between coronary artery calcification and calcium deposition in the myocardium. J Int Med Res 2019; 47:2910-2920. [PMID: 31117861 PMCID: PMC6683874 DOI: 10.1177/0300060519848587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Objectives To investigate the relationship between coronary artery calcification and calcium deposition in cardiomyocytes. Methods Patients who underwent valve replacement plus surgical ablation for atrial fibrillation, together with left atrial appendage resection, were included. Coronary artery calcification (CAC) score was evaluated prior to surgery using dual-source computed tomography. Samples of left atrial appendage tissue were collected to analyse the following indicators: calcium deposition, alkaline phosphatase activity, calcium content, protein levels of runt-related transcription factor 2 (Runx2), osteopontin and β-catenin, and mRNA levels of osteopontin, endothelin and ghrelin. Relationships between CAC score and various indicators were analysed by univariate logistic or linear regression. Results Out of tissue from eight patients, CAC score was not correlated with cardiomyocyte calcification (odds ratio [OR] 0.984 and OR 0.983; von Kossa or alizarin red staining, respectively). CAC score showed an inverse linear correlation with Runx2 protein (β = –0.75), but was not correlated with osteopontin (β = –0.52) or β-catenin protein (β = –0.56), mRNA levels of osteopontin, endothelin and ghrelin (β = 0.13, 0.02, and 0.02, respectively), alkaline phosphatase activity (β = 0.56), or calcium content (β = –0.22). Conclusions Coronary artery calcification was not correlated with calcium deposition in cardiomyocytes.
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Affiliation(s)
- Yue Wang
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Yu-Cai Hu
- 2 Department of Cardiology, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, China
| | - Yuan Zhou
- 3 Department of Cardiac Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Lei Zhao
- 4 Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Dong Chen
- 5 Department of Pathology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Lin-Ling Li
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Le Jiang
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Zi-Chuan Zhang
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Song-Nan Li
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Song-Nan Wen
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Yan-Fei Ruan
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Nian Liu
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Yan Qiao
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Qiang Lv
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Rong Hu
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Xin Du
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Xiao-Hui Liu
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Chang-Sheng Ma
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Jian-Zeng Dong
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
| | - Rong Bai
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Centre for Cardiovascular Diseases, Beijing, China
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Liu Z, Khalil RA. Evolving mechanisms of vascular smooth muscle contraction highlight key targets in vascular disease. Biochem Pharmacol 2018; 153:91-122. [PMID: 29452094 PMCID: PMC5959760 DOI: 10.1016/j.bcp.2018.02.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 02/12/2018] [Indexed: 12/11/2022]
Abstract
Vascular smooth muscle (VSM) plays an important role in the regulation of vascular function. Identifying the mechanisms of VSM contraction has been a major research goal in order to determine the causes of vascular dysfunction and exaggerated vasoconstriction in vascular disease. Major discoveries over several decades have helped to better understand the mechanisms of VSM contraction. Ca2+ has been established as a major regulator of VSM contraction, and its sources, cytosolic levels, homeostatic mechanisms and subcellular distribution have been defined. Biochemical studies have also suggested that stimulation of Gq protein-coupled membrane receptors activates phospholipase C and promotes the hydrolysis of membrane phospholipids into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 stimulates initial Ca2+ release from the sarcoplasmic reticulum, and is buttressed by Ca2+ influx through voltage-dependent, receptor-operated, transient receptor potential and store-operated channels. In order to prevent large increases in cytosolic Ca2+ concentration ([Ca2+]c), Ca2+ removal mechanisms promote Ca2+ extrusion via the plasmalemmal Ca2+ pump and Na+/Ca2+ exchanger, and Ca2+ uptake by the sarcoplasmic reticulum and mitochondria, and the coordinated activities of these Ca2+ handling mechanisms help to create subplasmalemmal Ca2+ domains. Threshold increases in [Ca2+]c form a Ca2+-calmodulin complex, which activates myosin light chain (MLC) kinase, and causes MLC phosphorylation, actin-myosin interaction, and VSM contraction. Dissociations in the relationships between [Ca2+]c, MLC phosphorylation, and force have suggested additional Ca2+ sensitization mechanisms. DAG activates protein kinase C (PKC) isoforms, which directly or indirectly via mitogen-activated protein kinase phosphorylate the actin-binding proteins calponin and caldesmon and thereby enhance the myofilaments force sensitivity to Ca2+. PKC-mediated phosphorylation of PKC-potentiated phosphatase inhibitor protein-17 (CPI-17), and RhoA-mediated activation of Rho-kinase (ROCK) inhibit MLC phosphatase and in turn increase MLC phosphorylation and VSM contraction. Abnormalities in the Ca2+ handling mechanisms and PKC and ROCK activity have been associated with vascular dysfunction in multiple vascular disorders. Modulators of [Ca2+]c, PKC and ROCK activity could be useful in mitigating the increased vasoconstriction associated with vascular disease.
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Affiliation(s)
- Zhongwei Liu
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Raouf A Khalil
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA.
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Esposito R, Manzo M, Hohenegger M, Pluvio M, Lanzetti N, Perna N, Romano-Carratelli C, Giordano C. Toxicity in Uremia 1. Correlation between PTH Levels and Depressed Cell Proliferation. Int J Artif Organs 2018. [DOI: 10.1177/039139888801100305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cell proliferation is significantly depressed in uremia; to assess the influence of PTH on it, normal lymphocytes were cultured in presence of uremic patients’ serum with low or high plasma PTH levels (Group A; PTH < 2.5 ng/ml; Group B: PTH > 12 ng/ml), and serum of normal subjects (Group C). Cell proliferation was lowered by serum from both groups (p A vs C < 0.004; p B vs C < 0.001). However, the depressing effect was more evident when group B serum was employed (p A vs B< 0.002).
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Affiliation(s)
- R. Esposito
- Institute of Internal Medicine and Nephrology, 1st Faculty, University of Naples - Italy
| | - M. Manzo
- Institute of Internal Medicine and Nephrology, 1st Faculty, University of Naples - Italy
| | - M. Hohenegger
- Institute of General and Experimental Pathology, University of Wien - Austria
| | - M. Pluvio
- Institute of Internal Medicine and Nephrology, 1st Faculty, University of Naples - Italy
| | - N. Lanzetti
- Institute of Internal Medicine and Nephrology, 1st Faculty, University of Naples - Italy
| | - N. Perna
- Institute of Internal Medicine and Nephrology, 1st Faculty, University of Naples - Italy
| | | | - C. Giordano
- Institute of Internal Medicine and Nephrology, 1st Faculty, University of Naples - Italy
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Sukumaran P, Schaar A, Sun Y, Singh BB. Functional role of TRP channels in modulating ER stress and Autophagy. Cell Calcium 2016; 60:123-32. [PMID: 26995055 DOI: 10.1016/j.ceca.2016.02.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 02/21/2016] [Accepted: 02/22/2016] [Indexed: 02/07/2023]
Abstract
Intracellular calcium (Ca(2+)) levels play a vital role in regulating cellular fate. The coordination and interrelation among the cellular organelles, mainly the intracellular Ca(2+) stores in endoplasmic reticulum (ER), are crucial in maintaining cytosolic Ca(2+) levels and in general cellular homeostasis. Moreover, maintaining Ca(2+) homeostasis is essential for regulating diverse and sometimes opposing processes such as cell survival and cell death in disease conditions such as, neurodegeneration, cancer and aging. Ca(2+) is able to regulate opposing functions by either regulating the cellular "self-eating" phenomenon of autophagy to promote cell survival or by regulating the programmed cell death process of apoptosis. Autophagy is also important for cell survival especially after induction of ER stress and association between ER stress and autophagy may have relevance to numerous diseases. Moreover, a multitude of evidence is emerging that the functional regulation of TRP channels, their unique localization, and their interaction with other Ca(2+)-sensing elements define these diverse regulatory pathways. It is this unique function which allows individual TRP channels to contribute differently in the regulation of cell fate and, in turn, determines the precise effect of modulating Ca(2+) signaling via the particular channel. Thus, in this review we have focused on the aspects of TRP channel localization and function (Ca(2+) signaling) that affects the ER stress and autophagic process.
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Affiliation(s)
- Pramod Sukumaran
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, United States
| | - Anne Schaar
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, United States
| | - Yuyang Sun
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, United States
| | - Brij B Singh
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, United States.
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Paquet F, Etherington G, Bailey MR, Leggett RW, Lipsztein J, Bolch W, Eckerman KF, Harrison JD. ICRP Publication 130: Occupational Intakes of Radionuclides: Part 1. Ann ICRP 2015; 44:5-188. [PMID: 26494836 DOI: 10.1177/0146645315577539] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This report is the first in a series of reports replacing Publications 30 and 68 to provide revised dose coefficients for occupational intakes of radionuclides by inhalation and ingestion. The revised dose coefficients have been calculated using the Human Alimentary Tract Model (Publication 100) and a revision of the Human Respiratory Tract Model (Publication 66) that takes account of more recent data. In addition, information is provided on absorption into blood following inhalation and ingestion of different chemical forms of elements and their radioisotopes. In selected cases, it is judged that the data are sufficient to make material-specific recommendations. Revisions have been made to many of the models that describe the systemic biokinetics of radionuclides absorbed into blood, making them more physiologically realistic representations of uptake and retention in organs and tissues, and excretion. The reports in this series provide data for the interpretation of bioassay measurements as well as dose coefficients, replacing Publications 54 and 78. In assessing bioassay data such as measurements of whole-body or organ content, or urinary excretion, assumptions have to be made about the exposure scenario, including the pattern and mode of radionuclide intake, physical and chemical characteristics of the material involved, and the elapsed time between the exposure(s) and measurement. This report provides some guidance on monitoring programmes and data interpretation.
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Olbrich HG, Michaelis H, Vandeplassche G, Borgers M, Oremek G, Krause E, Satter P, Kober G, Mutschler E, Kaltenbach M. Ultrastructural calcium distribution and myocardial calcium content in human idiopathic dilated cardiomyopathy. Cardiovasc Pathol 2015; 2:127-36. [PMID: 25990607 DOI: 10.1016/1054-8807(93)90024-v] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/1992] [Accepted: 12/31/1992] [Indexed: 02/07/2023] Open
Abstract
Myocardial calcium overload in chronic heart failure is still a debatable issue. The aim of this study was to investigate the myocardial calcium content and intracellular calcium distribution in end-stage dilated cardiomyopathy. The explanted hearts of 13 patients (9 male, 4 female, mean age 49 ± 12 years) undergoing heart transplantation because of end-stage dilated cardiomyopathy were examined. Samples were obtained from the right and left ventricular free wall and from the septum. Calcium and magnesium content were measured by atomic absorption spectrophotometry. Ultrastructural calcium distribution was examined in dilated cardiomyopathy using the phosphate-pyroantimonate method. Ultrastructural calcium distribution was also examined in left ventricular biopsies obtained from 3 patients (male, mean age 47 ± 3.6 years) with nonfailing hearts. The number of mitochondrial calcium precipitates was estimated morphometrically by a point counting method. Myocardial calcium and magnesium content in dilated cardiomyopathy did not differ significantly among the right and left ventricles and septum ranging from 8.5 to 10.8 mmol/kg dry weight. The phosphate-pyroantimonate method visualized calcium precipitates being confined to the sarcolemma, T-tubules, intercalated disks, and mitochondria in both nonfailing myocardium and dilated cardiomyopathy. Because mitochondria may act as buffers of cytoplasmic calcium, mitochondrial calcium precipitates served as a criterion for a possible cellular calcium overload. No differences in the amount of mitochondrial calcium deposits were observed between dilated cardiomyopathy and nonfailing hearts. The data suggest that there is no global myocardial calcium overload in human eng-stage dilated cardiomyopathy.
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Affiliation(s)
- H G Olbrich
- Zentrum der Inneren Medizin, Universität Frankfurt, Germany
| | - H Michaelis
- Zentrum der Inneren Medizin, Universität Frankfurt, Germany
| | | | - M Borgers
- Zentrum der Chirurgie, Universität Frankfurt, Germany
| | - G Oremek
- Zentrum der Inneren Medizin, Universität Frankfurt, Germany
| | - E Krause
- Janssen Research Foundation, Beerse, Belgium
| | - P Satter
- Janssen Research Foundation, Beerse, Belgium
| | - G Kober
- Zentrum der Inneren Medizin, Universität Frankfurt, Germany
| | - E Mutschler
- Pharmakologisches Institut für Naturwissenschaftler, Universität Frankfurt, Germany
| | - M Kaltenbach
- Zentrum der Inneren Medizin, Universität Frankfurt, Germany
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Sukumaran P, Sun Y, Vyas M, Singh BB. TRPC1-mediated Ca²⁺ entry is essential for the regulation of hypoxia and nutrient depletion-dependent autophagy. Cell Death Dis 2015; 6:e1674. [PMID: 25741599 PMCID: PMC4385947 DOI: 10.1038/cddis.2015.7] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/04/2014] [Accepted: 12/29/2014] [Indexed: 02/06/2023]
Abstract
Autophagy is a cellular catabolic process needed for the degradation and recycling of protein aggregates and damaged organelles. Although Ca2+ is suggested to have an important role in cell survival, the ion channel(s) involved in autophagy have not been identified. Here we demonstrate that increase in intracellular Ca2+ via transient receptor potential canonical channel-1 (TRPC1) regulates autophagy, thereby preventing cell death in two morphologically distinct cells lines. The addition of DMOG or DFO, a cell permeable hypoxia-mimetic agents, or serum starvation, induces autophagy in both epithelial and neuronal cells. The induction of autophagy increases Ca2+ entry via the TRPC1 channel, which was inhibited by the addition of 2APB and SKF96365. Importantly, TRPC1-mediated Ca2+ entry resulted in increased expression of autophagic markers that prevented cell death. Furthermore, hypoxia-mediated autophagy also increased TRPC1, but not STIM1 or Orai1, expression. Silencing of TRPC1 or inhibition of autophagy by 3-methyladenine, but not TRPC3, attenuated hypoxia-induced increase in intracellular Ca2+ influx, decreased autophagy, and increased cell death. Furthermore, the primary salivary gland cells isolated from mice exposed to hypoxic conditions also showed increased expression of TRPC1 as well as increase in Ca2+ entry along with increased expression of autophagic markers. Altogether, we provide evidence for the involvement of Ca2+ influx via TRPC1 in regulating autophagy to protect against cell death.
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Affiliation(s)
- P Sukumaran
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, USA
| | - Y Sun
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, USA
| | - M Vyas
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, USA
| | - B B Singh
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58201, USA
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10
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Richardson RB. A physiological skeletal model for radionuclide and stable element biokinetics in children and adults. HEALTH PHYSICS 2010; 99:471-482. [PMID: 20838088 DOI: 10.1097/hp.0b013e3181d0cd4a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A physiological skeletal model (PSM) is described that represents the skeletal uptake, retention, and clearance of both bone-surface-seeking and bone-volume-seeking radionuclides and stable elements. A key objective of the PSM is to model the higher skeletal growth and bone turnover in infants and children (compared to adults) in order to account for their greater uptake and cancer risk from bone-seeking contaminants such as lead and plutonium. The PSM is a compartmental model that allows for the incorporation of organic and inorganic material in the bone volume via quiescent bone surfaces, forming bone surfaces and the lacuno-canaliculi system. The model uniquely incorporates a tertiary phase of mineralization via bone fluids. The PSM's structural concepts and biokinetic parameters--such as realistic mass transfers, organ and tissue masses, and bone remodeling half-times--are selected mainly on the basis of physiological and anatomical criteria. For brevity, model parameter values are evaluated for adults only. The PSM is an improvement on existing skeletal models that are based more on compartment structures and pathways that rendered good fits to biokinetic data rather than on being anatomically and physiologically accurate.
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Affiliation(s)
- Richard B Richardson
- Radiological Protection Research and Instrumentation Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ON K0J 1J0, Canada.
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Huttunen JK, Pietinen P, Nissinen A, Puska P. Dietary factors and hypertension. ACTA MEDICA SCANDINAVICA. SUPPLEMENTUM 2009; 701:72-82. [PMID: 3907297 DOI: 10.1111/j.0954-6820.1985.tb08892.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
There is increasing evidence that nutritional factors are critical in the pathogenesis of essential hypertension typical for acculturated societies. These factors include sodium, potassium, calcium, alcohol, and type and level of fat in the diet. More research is needed, however, before the role of various nutrients in the prevention and treatment of hypertension will be ascertained.
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Nabeshima YI. Discovery of alpha-Klotho unveiled new insights into calcium and phosphate homeostasis. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2009; 85:125-41. [PMID: 19282648 PMCID: PMC3524302 DOI: 10.2183/pjab.85.125] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 01/27/2009] [Indexed: 05/27/2023]
Abstract
alpha-Klotho was first identified as the responsible gene in a mutant mouse line whose disruption results in a variety of premature aging-related phenotypes. alpha-Klotho has been shown to participate in the regulation of parathyroid hormone secretion and trans-epithelial transport of Ca(2+) in the choroid plexus and kidney. alpha-Klotho, acting as a cofactor for FGF23, is also a major regulator of vitamin D biosynthesis and phosphate reabsorption in the kidney. These suggest that alpha-Klotho is a key player that integrates a multi-step regulatory system of calcium and phosphate homeostasis. Collectively, the molecular function of alpha-Klotho reveals a new paradigm that may change current concepts in mineral homeostasis and give rise to new insights in this field.
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Affiliation(s)
- Yo-ichi Nabeshima
- Department of Pathology and Tumor Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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Coburn CG, Currás-Collazo MC, Kodavanti PRS. In vitro effects of environmentally relevant polybrominated diphenyl ether (PBDE) congeners on calcium buffering mechanisms in rat brain. Neurochem Res 2007; 33:355-64. [PMID: 17846885 DOI: 10.1007/s11064-007-9430-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 06/29/2007] [Indexed: 11/26/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) are widely used as additive flame-retardants and have been detected in human blood, adipose tissue, and breast milk. Developmental and long-term exposures to these chemicals may pose a human health risk, especially to children. We have previously demonstrated that polychlorinated biphenyls (PCBs), which are structurally similar to PBDEs and cause neurotoxicity, perturb intracellular signaling events including calcium homeostasis and protein kinase C translocation, which are critical for neuronal function and development of the nervous system. The objective of the present study was to test whether environmentally relevant PBDE congeners 47 and 99 are also capable of disrupting Ca(2+) homeostasis. Calcium buffering was determined by measuring (45)Ca(2+)-uptake by microsomes and mitochondria, isolated from adult male rat brain (frontal cortex, cerebellum, hippocampus, and hypothalamus). Results show that PBDEs 47 and 99 inhibit both microsomal and mitochondrial (45)Ca(2+)-uptake in a concentration-dependent manner. The effect of these congeners on (45)Ca(2+)-uptake is similar in all four brain regions though the hypothalamus seems to be slightly more sensitive. Among the two preparations, the congeners inhibited (45)Ca(2+)-uptake in mitochondria to a greater extent than in microsomes. These results indicate that PBDE 47 and PBDE 99 congeners perturb calcium signaling in rat brain in a manner similar to PCB congeners, suggesting a common mode of action of these persistent organic pollutants.
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Affiliation(s)
- Cary G Coburn
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA
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Yamakage M, Namiki A. Calcium channels--basic aspects of their structure, function and gene encoding; anesthetic action on the channels--a review. Can J Anaesth 2002; 49:151-64. [PMID: 11823393 DOI: 10.1007/bf03020488] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
PURPOSE To review recent findings concerning Ca(2+) channel subtype/structure/function from electrophysiological and molecular biological studies and to explain Ca(2+) channel diseases and the actions of anesthetics on Ca(2+) channels. SOURCE The information was obtained from articles published recently and from our published work. PRINCIPAL FINDINGS Voltage-dependent Ca(2+) channels serve as one of the important mechanisms for Ca(2+) influx into the cells, enabling the regulation of intracellular concentration of free Ca(2+). Recent advances both in electrophysiology and in molecular biology have made it possible to observe channel activity directly and to investigate channel functions at molecular levels. The Ca(2+) channel can be divided into subtypes according to electrophysiological characteristics, and each subtype has its own gene. The L-type Ca(2+) channel is the target of a large number of clinically important drugs, especially dihydropyridines, and binding sites of Ca(2+) antagonists have been clarified. The effects of various kinds of anesthetics in a variety of cell types have been demonstrated, and some clinical effects of anesthetics can be explained by the effects on Ca(2+) channels. It has recently become apparent that some hereditary diseases such as hypokalemic periodic paralysis result from calcium channelopathies. CONCLUSION Recent advances both in electrophysiology and in molecular biology have made it possible to clarify the Ca(2+) channel structures, functions, genes, and the anesthetic actions on the channels in detail. The effects of anesthetics on the Ca(2+) channels either of patients with hereditary channelopathies or using gene mutation techniques are left to be discovered.
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Affiliation(s)
- Michiaki Yamakage
- Department of Anesthesiology Sapporo Medical University School of Medicine Sapporo Hokkaido Japan.
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Barbagallo M, Gupta RK, Dominguez LJ, Resnick LM. Cellular ionic alterations with age: relation to hypertension and diabetes. J Am Geriatr Soc 2000; 48:1111-6. [PMID: 10983912 DOI: 10.1111/j.1532-5415.2000.tb04788.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Cytosolic free calcium (Cai) and magnesium (Mgi) are vital to cellular homeostasis and function. OBJECTIVE To evaluate cellular divalent cations in normal subjects at different ages and their relationship to ion levels in essential hypertension and diabetes. DESIGN A cross-sectional study. SETTING A university hospital in New York. PARTICIPANTS A total of 103 subjects (32 older, 71.1 +/- 1.2 y/o, and 71 young/middle aged subjects, 51.1 +/- 2.3 y/o). INTERVENTION Oral glucose tolerance test. MEASUREMENTS 19F and 31P NMR spectroscopy were used to measure Cai and Mgi levels in erythrocytes from normal (>65 y/o, n = 11; <65 y/o, n = 26), hypertensive (EH) (>65 y/o, n = 9; <65 y/o, n = 30), and type 2 diabetic (DM) (>65 y/o, n = 12; <65 y/o, n = 15) subjects; these levels were also compared with glucose and insulin levels before and after oral glucose loading. RESULTS Fasting Mgi levels were lower (207 +/- 7.8 vs 236 +/- 7.5 microM; P < .05) and Cai higher (32.2 +/- 3.0 vs 20.3 +/- 1.8 nM; P < .05) in older than in younger normal subjects. For all normal subjects, the greater the age, the higher the Cai (r = 0.622, P = .004) and the lower the Mgi (r = -0.423; P = .011). However, no significant (P = NS) differences in Mgi or Cai levels were observed between older normal and young/middle-aged subjects with EH (Mgi = 189.7 +/- 5.9 vs 182.6 +/- 9.8 microM; Cai = 33.8 +/- 4.9 vs 35.6 +/- 4.0 nM) or DM (Mgi = 182.8 +/- 10.9 vs 180.8 +/- 8.1 microM; Cai = 33.6 +/- 4.3 vs 39.7 +/- 5.9 nM). Significant relationships were also found between cellular ion content, blood pressure, and glycemic indices. CONCLUSIONS Aging is associated with the onset of altered Cai and Mgi levels, indistinguishable from those observed in hypertension and diabetes, independent of age. We suggest that these ionic changes may be clinically significant, underlying the predisposition of older subjects to cardiovascular and metabolic diseases.
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Affiliation(s)
- M Barbagallo
- Institute of Internal Medicine and Geriatrics, University of Palermo, Italy
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Barbagallo M, Dominguez LJ, Licata G, Resnick LM. Effects of aging on serum ionized and cytosolic free calcium: relation to hypertension and diabetes. Hypertension 1999; 34:902-6. [PMID: 10523382 DOI: 10.1161/01.hyp.34.4.902] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Elevated cytosolic free calcium (Ca(i)) and reciprocally reduced, extracellular ionized calcium (Ca-ion) levels are observed in both hypertension and non-insulin-dependent diabetes mellitus (NIDDM). Because the changes of vascular function and insulin sensitivity in these conditions resemble the changes associated with "normal" aging, we wondered to what extent similar alterations in calcium metabolism occur with aging per se in the absence of overt hypertension or diabetes. We therefore measured platelet Ca(i) levels by spectrofluorometry and serum Ca-ion levels in normotensive, nondiabetic, healthy, normal, elderly (>65 years old) subjects, mean age +/-SEM, 72.2+/-1.5 years old (n=11); in healthy, normal, young (<65 years old) adults, 46.1+/-2.3 years old (n=12); in 10 young adult hypertensives, 48.6+/-1.9 years old; and in 10 normotensive NIDDM subjects, 49.2+/-1.6 years old. Platelet Ca(i) levels were higher (104.5+/-4.9 versus 80.2+/-1.8 nmol/L, P<0.01) and Ca-ion levels lower (1.212+/-0.010 versus 1.236+/-0.011 mmol/L, P<0.05) in normal elderly compared with young control subjects, but normal elderly Ca(i) and Ca-ion levels were indistinguishable from those in hypertensive (Ca(i) 107.5+/-3.6 nmol/L, Ca-ion 1.210+/-0.009 mmol/L) and NIDDM (Ca(i) 110.7+/-4.7 nmol/L, Ca-ion 1.204+/-0.014 mmol/L) subjects. In normal subjects, significant correlations were found between platelet Ca(i) levels and age (r=0.655, P<0.01) and between Ca(i) levels and systolic blood pressure (r=0.733, P<0.001). We conclude that aging is associated with alterations of Ca(i) and Ca-ion levels resembling those changes present at any age in hypertension and type 2 diabetes. We hypothesize that these alterations of calcium metabolism underlie the predisposition to the alterations of blood pressure and insulin sensitivity characteristic of "normal" aging. The data also suggest that studies of the aging process should be limited to subjects with normal blood pressure and glucose tolerance.
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Affiliation(s)
- M Barbagallo
- Institute of Internal Medicine and Geriatrics, University of Palermo, Palermo, Italy.
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17
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Kobayashi S, Miescher E, Clemens MG. A synergistic effect of extracellular hypocalcemic condition for hyperoxic reoxygenation injury in rat hepatocytes. Transplantation 1999; 67:451-7. [PMID: 10030294 DOI: 10.1097/00007890-199902150-00019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Calcium accumulation of cells and mitochondria during reperfusion or reoxygenation has been implicated as a potential factor in cell injury as the result of mitochondrial damage. The objective of this study was to disclose whether or not low extracellular calcium ion concentration ([Ca2+]ex) in the medium at the time of reoxygenation might prevent calcium accumulation and attenuate hepatocytes injury after severe hypoxia. METHODS Isolated rat hepatocytes were incubated under a hyperoxic or hypoxic atmosphere for 60 min. During the ensuing 60-min hyperoxic reoxygenation, medium [Ca2+]ex was varied from 0.6 microM to 2.0 mM by altering total calcium and addition of chelators. RESULTS Incubation in low [Ca2+]ex reduced total cellular calcium and mitochondrial calcium in both the hyperoxic and hypoxic group. Under hyperoxic/hyperoxic incubation (control), hepatocytes were able to maintain potassium balance when [Ca2+]ex was >3.0 microM (pCa=5.5) and cellular viability (% lactate dehydrogenase release) at all levels of extracellular calcium. Under hypoxic/hyperoxic incubation (reoxygenation), however, loss of the ability to restore potassium balance as well as apparent increase in lactate dehydrogenase release were observed at severely low [Ca2+]ex (<30 microM; pCa=4.5). This low [Ca2+]ex-induced exacerbation of hepatocytes viability could not be generated under mild reoxygenation such as normoxia. CONCLUSIONS In normal isolated hepatocytes, very low [Ca2+]ex levels produce only very subtle changes in membrane permeability of isolated hepatocytes. After hypoxia, however, hypocalcemia acts synergistically with hyperoxic reoxygenation to produce more severe damage. These results suggested that [Ca2+]ex should be maintained on the physiological level to attenuate hepatocytes injury after severe hypoxia.
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Affiliation(s)
- S Kobayashi
- Division of Pediatric Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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19
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Abstract
Calcium and sodium absorption by the kidney normally proceed in parallel. However, a number of physiological, pharmacological, pathological, and genetic conditions dissociate this relation. In each instance, the dissociation can be traced to the distal convoluted tubule, where calcium and sodium transport are inversely related. Based on the identification of the relevant sodium transporters in these cells and on analysis of the mechanism of calcium transport, an explanation for this inverse relation can be developed. Apical membrane calcium entry is mediated by voltage-sensitive calcium channels that are activated upon membrane hyperpolarization. Basolateral calcium efflux is effected primarily by Na+/Ca2+ exchange. According to the model, inhibition of sodium entry through either the Na-Cl cotransporter or the Na+ channel hyperpolarizes the cell, as does parathyroid hormone, thereby activating the calcium entry channel and increasing the driving force for diffusional entry. Membrane hyperpolarization also increases the driving force of calcium efflux through the Na+/Ca2+ exchanger. Thus sodium-dependent changes of calcium transport are indirect and occur secondarily through effects on membrane voltage.
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Affiliation(s)
- P A Friedman
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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20
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Doğrul A, Yeşilyurt O. Effects of intrathecally administered aminoglycoside antibiotics, calcium-channel blockers, nickel and calcium on acetic acid-induced writhing test in mice. GENERAL PHARMACOLOGY 1998; 30:613-6. [PMID: 9522184 DOI: 10.1016/s0306-3623(97)00335-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
1. Antinociceptive effects of intrathecally administered aminoglycoside antibiotics, calcium-channel blockers, nickel and calcium ions on the acetic acid-induced writhing test in mice were examined. 2. Neomycin (0.5-20.0 micrograms/mouse) gentamicin (5-40 micrograms/mouse), nicardipine, diltiazem and verapamil (0.5-80.0 micrograms/mouse) and calcium ions (0.02-1.0 mumol/mouse) exerted a dose-dependent antinociceptive activity on the acetic acid-induced writhing test. Nickel ions (2.5, 5.0 and 10.0 mumol/mouse) were found ineffective in this test. 3. These results suggest that N- and L-type, but not T-type, voltage-dependent calcium channels are implicated in the spinal processing of nociceptive information.
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Affiliation(s)
- A Doğrul
- Department of Pharmacology, Faculty of Medicine, Gülhane Medical Military Academy, Etlik, Ankara, Turkey
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Affiliation(s)
- F C Mooren
- Medizinische Klinik und Poliklinik B, Westfälische Wilhelm-Universität, Münster, Germany
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22
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Dominguez LJ, Ruggero R, Bruno D, Catalano G, La Milia DA, Barbagallo M. Calcium Metabolism in the Elderly. RECENT ADVANCES IN GERIATRICS 1998:239-250. [DOI: 10.1007/978-1-4899-1483-5_26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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23
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Barbagallo M, Dominguez LJ, Licata A, Granvillano L, Alessi MA, Licata G, Resnick LM. The Ionic Hypothesis of Aging. RECENT ADVANCES IN GERIATRICS 1998:25-36. [DOI: 10.1007/978-1-4899-1483-5_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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24
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Sowa G, Przewłocki R. Ouabain enhances the lipopolysaccharide-induced nitric oxide production by rat peritoneal macrophages. IMMUNOPHARMACOLOGY 1997; 36:95-100. [PMID: 9130001 DOI: 10.1016/s0162-3109(96)00159-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Incubation of rat peritoneal macrophages with the bacterial product lipopolysaccharide (LPS) caused significant increases in the production of nitrite, a stable endproduct of nitric oxide (NO). Addition of the digitalis-derived glycoside ouabain, which alone is without effect, significantly enhanced the stimulating effects of LPS. The Na+ ionophore monensin was without any effect, while the Ca2+ ionophore A23187, like ouabain, enhanced the effect of LPS. Thus ouabain may enhance the LPS-stimulated NO production in rat peritoneal macrophages via still unknown mechanisms in which Ca2+ ions are most likely involved.
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Affiliation(s)
- G Sowa
- Department of Molecular Neuropharmacology, Polish Academy of Sciences, Krakow, Poland
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25
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Chapter 9 Plant Gravitropic Response. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1569-2574(08)60084-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
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26
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Mallick BN, Gulyani S. Alterations in synaptosomal calcium concentrations after rapid eye movement sleep deprivation in rats. Neuroscience 1996; 75:729-36. [PMID: 8951869 DOI: 10.1016/0306-4522(96)00177-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Rapid eye movement sleep deprivation alters behavioral and physiological, as well as cellular functioning and responsiveness. Since intracellular calcium concentration plays an important role in regulating cellular functions, it was hypothesized that such deprivation might induce changes in intracellular calcium concentration. Therefore, in this study, rats were deprived of rapid eye movement sleep by the flower-pot technique, and total, bound and free calcium concentrations were estimated in synaptosomal preparations from the cerebrum, cerebellum, brainstem, midbrain, pons and medulla. Rapid eye movement sleep deprivation was continued for two or four days and suitable control experiments were conducted to rule out the effects of non-specific factors. Total calcium concentration increased in the brainstem but showed a decrease in the cerebellum and cerebrum. After four days deprivation, the free calcium concentration always decreased; however, the bound calcium concentration decreased in the cerebrum and cerebellum but increased in the brainstem. After two days' deprivation, the medulla was the only region where the bound calcium increased while the free form decreased; only the free form decreased in the pons, while the midbrain was never affected. The results suggest that there was a net efflux of calcium in the cerebellum and cerebrum, but a net influx in the brainstem. The findings support our hypothesis and help to explain earlier observations. Since it is known that calcium plays an important role in cellular functioning, these changes in calcium concentration may be the underlying mechanism for rapid eye movement sleep deprivation-induced cellular expressions and behavior of neurons.
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Affiliation(s)
- B N Mallick
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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27
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Locker FG. HORMONAL REGULATION OF CALCIUM HOMEOSTASIS. Nurs Clin North Am 1996. [DOI: 10.1016/s0029-6465(22)00188-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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28
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Picotto G, Massheimer V, Boland R. Acute stimulation of intestinal cell calcium influx induced by 17 beta-estradiol via the cAMP messenger system. Mol Cell Endocrinol 1996; 119:129-34. [PMID: 8807632 DOI: 10.1016/0303-7207(96)03799-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent studies have provided evidence for nuclear estrogen receptor-mediated calcium transport in intestinal mucosal cells. The possibility that, in addition, estrogens directly stimulate intestinal Ca2+ fluxes through second-messenger pathways was investigated. Exposure of enterocytes isolated from female rat duodenum to low physiological levels of 17 beta-estradiol (10(-11), 10(-10) and 10(-8) M) rapidly (1-10 min) increased (50-170%) cell 45Ca2+ influx. 17 alpha-Estradiol, dihydrotestosterone and progesterone were devoid of activity, suggesting specificity of the estrogen effect. Maximum responses induced by 17 beta-estradiol (5 min at 10(-10) M) could be abolished to a great extent (84%) by pretreating the cells with verapamil (10 microM) and nitrendipine (1 microM), involving the activation of voltage-dependent Ca2+ channels in the fast increase of rat duodenal calcium uptake by the hormone. Evidence was obtained indicating that the acute estrogen stimulation of enterocyte Ca2+ influx is mediated by the cyclic AMP/PKA pathway. 17 beta-Estradiol rapidly increased cAMP content of rat duodenal cells in parallel to the changes in Ca2+ uptake. In addition, forskolin, dibutyryl cAMP and Sp-cAMPS mimicked and Rp-cAMPS suppressed the prompt 17 beta-estradiol-induced stimulation of Ca2+ influx. These results are consistent with a direct action of estrogens in the enterocyte, presumably a non-genomic one, initiated on the cell surface and resulting in rapid activation of the cAMP pathway and Ca2+ channels, which may be relevant for regulation of intestinal calcium transport.
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Affiliation(s)
- G Picotto
- Departamento de Biologia y Bioquimica, Universidad Nacional del Sur, Bahia Blanca, Argentina
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29
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Kodavanti PR, Ward TR, McKinney JD, Tilson HA. Inhibition of microsomal and mitochondrial Ca2+-sequestration in rat cerebellum by polychlorinated biphenyl mixtures and congeners. Structure-activity relationships. Arch Toxicol 1996; 70:150-7. [PMID: 8825671 DOI: 10.1007/s002040050254] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent studies from our laboratory indicate that polychlorinated biphenyl (PCB) congeners in vitro perturbed signal transduction mechanisms including cellular Ca2+-homeostasis and protein kinase C translocation. We have now investigated the structure-activity relationship (SAR) of three PCB mixtures, 24 PCB congeners and one dibenzofuran for their effects on microsomal and mitochondrial Ca2+-sequestration in rat cerebellum. Ca2+-sequestration by these intracellular organelles was determined using radioactive 45CaCl2. All three mixtures studied, Aroclor 1016, Aroclor 1254 and Aroclor 1260, were equally potent in inhibiting microsomal and mitochondrial Ca2+-sequestration with IC50 values of 6-8 microM. 1,2,3,7,8-Pentachlorodibenzofuran had no effect on Ca2+-sequestration by these organelles. The SAR among the congeners revealed: (1) congeners with ortho-/meta- or ortho-, para-chlorine substitutions were the most potent in inhibiting microsomal and mitochondrial Ca2+-sequestration (IC50 = 2.4-22.3 microM); (2) congeners with only para- but without ortho-substitutions were not effective in inhibiting Ca2+-sequestration by microsomes and mitochondria; (3) increased chlorination was not related to the effectiveness of these congeners. The present SAR studies indicate that the effects of most PCB congeners in vitro may be related to an interaction at specific sites having preference for low lateral substitution or lateral content (meta- or para) in the presence of ortho-substitution.
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Affiliation(s)
- P R Kodavanti
- Neurotoxicology Division, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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30
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Affiliation(s)
- A J Knox
- Respiratory Medicine Unit, City Hospital, Nottingham, UK
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31
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Brochiero E, Raschi C, Ehrenfeld J. Na/Ca exchange in the basolateral membrane of the A6 cell monolayer: role in Cai homeostasis. Pflugers Arch 1995; 430:105-14. [PMID: 7667070 DOI: 10.1007/bf00373845] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The presence of a Na/Ca exchanger in A6 cells was investigated by measuring intracellular calcium (Cai) fluctuations and the 45Ca fluxes through the basolateral membranes (blm) of the cell monolayer. Removal of Na+ from the medium produced a transient increase in Cai followed by a regulatory phase returning Cai to control levels in 3-4 min, this phase being greatly accelerated (< 60 s) by NaCl addition (apparent Km of approximately 5 mM Na+). The Cai increase was only found with the Na(+)-free medium on the basolateral side of the cell monolayer. A twofold increase in the 45Ca influx was observed under these conditions. In Ca(2+)- depleted cells, the initial Cai increase after Ca2+ addition to the medium was greater when the putative Na/Ca exchanger was not functioning (i.e. in a Na(+)-free medium). 45Ca effluxes through the blm of the monolayer were greatly and transiently increased by a Na(+)-free medium on the serosal side and blocked by orthovanadate (1 mM). The Cai increased induced by a hypo-osmotic shock was greater in cells bathed in a Na(+)-medium, conditions expected to block the activity of the Na/Ca exchanger. These findings support the hypothesis that a Na/Ca exchanger is present on the blm of A6 cells and affirm its role in Cai homeostasis in steady-state conditions and following osmotic shock. In addition, a Ca2+ pump also located on the blm and Ca2+ stores sensitive to inositol 1,4,5-trisphosphate were found to be implicated in Cai homeostasis.
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Affiliation(s)
- E Brochiero
- Department of Cellular and Molecular Bilogy CEA/URA 1855 (CNRS), Villefranche/Mer, France
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Mertens MJ, Pfaffendorf M, Van Zwieten PA. Sensitivity of cardiac tissues with moderate and advanced hypertrophy to calcium ions. GENERAL PHARMACOLOGY 1995; 26:399-406. [PMID: 7590094 DOI: 10.1016/0306-3623(94)00181-l] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
1. Prolonged existence of hypertension is known to induce a compensatory increase in cardiac weight, later followed by a loss of functional responsiveness to biological stimuli. 2. It was the aim of the present study to investigate the functional responses of hypertrophied hearts to rising levels of intracellular calcium. The experiments were performed using two different degrees of cardiac hypertrophy, the first as obtained in spontaneously hypertensive rats (SHR) of 18-20 weeks old, the second by using rats, 32-34 weeks old, with a surgically induced stenosis of the thoracic aorta (ASR). The ASR, which showed signs of overt heart failure, may be presented as a model for hypertension-induced end-stage cardiac hypertrophy. Age-matched normotensive Wistar-Kyoto rats (WKY) and sham-operated Wistar rats served as respective controls. 3. Different methods were employed such as increasing the extracellular Ca2+ concentration, stimulation of calcium influx by means of the calcium entry promoter Bay K 8644, or altering the sodium-calcium exchange by means of the sodium ionophore monensin. 4. The inotropic responses induced by increasing the extracellular Ca2+ concentration or provoked by the calcium entry promoter Bay K 8644 proved more pronounced in hearts taken from SHR of 18 weeks old than in those from normotensive control rats, whereas the response to monensin was found to be the same in both types of hearts. In the hearts of ASR, however, the inotropic responses to Ca2+, Bay K 8644 and monensin were strongly impaired. 5. These data demonstrate that in functional experiments the sensitivity to Ca2+, which represents the main pathway in establishing a contraction, is strongly reduced in advanced cardiac hypertrophy.
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Affiliation(s)
- M J Mertens
- Department of Pharmacotherapy, Faculty of Medicine, University of Amsterdam, Academic Medical Center, The Netherlands
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Mestdagh N, Vandewalle B, Hornez L, Hénichart JP. Comparative study of intracellular calcium and adenosine 3',5'-cyclic monophosphate levels in human breast carcinoma cells sensitive or resistant to Adriamycin: contribution to reversion of chemoresistance. Biochem Pharmacol 1994; 48:709-16. [PMID: 8080443 DOI: 10.1016/0006-2952(94)90048-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Multidrug resistance (MDR) corresponds to the cross-over resistance of tumour cells to structurally unrelated cytotoxic chemotherapeutic drugs. One of the mechanisms causing this resistance is the enhanced expression of a transmembrane drug efflux pump P-glycoprotein (P-170). Reversal of P-glycoprotein-associated MDR has received much attention in recent years. In experimental cell lines, P-170 and the glutathione redox cycle seem to contribute to this phenomenon; P-170 may be inactivated by calcium and calmodulin antagonists and the glutathione redox cycle altered by buthionine sulphoximine (BSO). Treatment of human MCF-7 breast cancer cells with chemosensitizers (CS), such as verapamil, trifluoperazine or BSO, for 72 hr resulted in an enhanced sensitization of cells to Adriamycin, trifluoperazine being the most potent compound in the reversion of chemoresistance. In these Adriamycin sensitive or resistant cells, treated or not by the CS, the possible role of calcium and cyclic adenosine monophosphate (cAMP) in mediating the reversion of chemoresistance to Adriamycin was investigated. It was found that intracellular calcium was approximately 2-fold higher in resistant than in sensitive cells, the opposite was true for cAMP. Modifications in calcium and cAMP levels were observed in MCF-7 resistant cells after treatment with verapamil and BSO; trifluoperazine had no effect on these two parameters. These results seemed to rule out any implication of calcium and cAMP levels in the contribution of these three chemosensitizers in the mechanisms of reversion of chemoresistance to Adriamycin.
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Affiliation(s)
- N Mestdagh
- Centre de Recherches INSERM, Lille, France
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Wadhwani KC, Rapoport SI. Transport properties of vertebrate blood-nerve barrier: comparison with blood-brain barrier. Prog Neurobiol 1994; 43:235-79. [PMID: 7816928 DOI: 10.1016/0301-0082(94)90002-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- K C Wadhwani
- Laboratory of Neurosciences, NIA, NIH, Bethesda, MD 20892
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Eichler ME, Dubinsky JM, Tong J, Rich KM. The ability of diphenylpiperazines to prevent neuronal death in dorsal root ganglion neurons in vitro after nerve growth factor deprivation and in vivo after axotomy. J Neurochem 1994; 62:2148-57. [PMID: 8189223 DOI: 10.1046/j.1471-4159.1994.62062148.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The mechanism of neuroprotection by the calcium channel antagonist flunarizine against neuronal death is unknown. We investigated the ability of other calcium channel antagonists (cinnarizine, nimodipine, nicardipine, diltiazem, and verapamil), calmodulin antagonists, and calpain inhibitors to prevent neuronal death in rat dorsal root ganglion neurons in vitro after nerve growth factor (NGF) deprivation and the ability of cinnarizine and diltiazem to protect in vivo after axotomy. In vitro, only neurons treated with cinnarizine or flunarizine were protected from death after withdrawal. In vivo, cinnarizine, but not diltiazem, protected dorsal root ganglion neurons in rats after unilateral sciatic nerve crush. Intracellular calcium concentration ([Ca2+]i) was evaluated with fura 2 after NGF deprivation in vitro. Neurons "committed to die" 24 h after NGF deprivation displayed a decline in [Ca2+]i before visible morphological deterioration consistent with cell death. The influx of extracellular calcium was not necessary to produce neuronal death. Neurons deprived of NGF gradually lost the ability to respond to elevated external potassium with an increase in [Ca2+]i during the first 24 h after trophic factor deprivation. After 24 h, neurons deprived of NGF could not be rescued by readministration of NGF. Neurons protected from cell death with diphenylpiperazines maintained their response to high external potassium, suggesting continued membrane integrity. We speculate that diphenylpiperazines may protect sensory neurons via an unknown mechanism that stabilizes cell membranes.
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Affiliation(s)
- M E Eichler
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri 78284-7756
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Wall M, O'Flaherty V, Ginty F, Houghton JA. Measurement of intracellular calcium levels of human spermatozoa acrosome reacted by electropermeabilization. ARCHIVES OF ANDROLOGY 1994; 32:185-95. [PMID: 8074573 DOI: 10.3109/01485019408987785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Human spermatozoa readily undergo in vitro capacitation and the acrosome reaction when exposed to a single, brief, high-voltage electric pulse in a medium containing calcium. Using the fluorescent calcium indicator, Fura-2, the changes in the intracellular calcium concentration of human sperm following exposure to voltages in the range of 200-2000 V cm-1 were measured. The induction of the acrosome reaction by the electropermeabilization pulse was also monitored. In comparison, changes in calcium uptake during a standard capacitation procedure in which sperm samples were incubated for 7 h were analyzed. At hourly intervals, acrosome reaction induction and intracellular calcium uptake were measured. The results indicate that electropermeabilization rapidly and efficiently produces high populations of acrosome-reacted sperm and a corresponding and associated increase in the intracellular calcium concentration.
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Affiliation(s)
- M Wall
- Department of Microbiology, University College, Galway, Ireland
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Pokuden N, Menshikov M, Robertson D, Robertson R, Orlov S, Tkachuk V, Postnov Y. Raised free calcium in the platelet of the spontaneously hypertensive rat: Regulation by adenosine diphosphate and epinephrine. Curr Ther Res Clin Exp 1994. [DOI: 10.1016/s0011-393x(05)80172-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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38
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Affiliation(s)
- F Cohadon
- Clinique Universitaire de Neurochirurgie Hôpital Pellegrin Tripode, Bordeaux, France
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39
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Hyde GE, Durham D. Rapid increase in mitochondrial volume in nucleus magnocellularis neurons following cochlea removal. J Comp Neurol 1994; 339:27-48. [PMID: 8106659 DOI: 10.1002/cne.903390105] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Second-order auditory neurons in nucleus magnocellularis (NM) of the chick brainstem undergo a series of rapid metabolic changes following unilateral cochlea removal, culminating in the death of 25% of NM neurons. Within hours of cochlea removal, ipsilateral NM neurons show marked increases in histochemical staining for the mitochondrial enzymes succinate dehydrogenase and cytochrome oxidase. We investigated corresponding ultrastructural changes in NM neurons by preparing animals undergoing unilateral cochlea removal for transmission electron microscopy. We quantified changes in NM mitochondrial volume by stereological methods and qualitatively compared mitochondrial morphology between NM neurons destined to survive and those destined to die after cochlea removal. Within hours of cochlea removal, ipsilateral NM neurons show striking increases in mitochondrial volume (84% at 6 hours and 236% at 12 hours after cochlea removal compared to unoperated, control animals). At 2 week survival times, ipsilateral NM neurons contain fewer mitochondria than contralateral neurons. Surprisingly, anesthesia alone causes short-term increases in NM mitochondrial volume. Animals anesthetized with pentobarbital and ketamine and sacrificed 6 or 12 hours later showed a 45% increase in mitochondrial volume compared to previously unanesthetized animals. NM neurons destined to die within days of cochlea removal can be identified within several hours after deafferentation by the appearance of their ribosomes. We observed qualitative differences in mitochondrial morphology in dying neurons. Mitochondria in neurons destined to die consistently showed mitochondrial swelling and vacuolization indicative of metabolic dysfunction. Similar mitochondrial changes have been reported when mitochondria take up excess calcium. Ultrastructural changes in NM after cochlea removal display features of both programmed and pathological cell death, in which increased intracellular calcium is thought to play a role.
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Affiliation(s)
- G E Hyde
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle 98195
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40
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Bygrave FL, Benedetti A. Calcium: its modulation in liver by cross-talk between the actions of glucagon and calcium-mobilizing agonists. Biochem J 1993; 296 ( Pt 1):1-14. [PMID: 8250828 PMCID: PMC1137647 DOI: 10.1042/bj2960001] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- F L Bygrave
- Division of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra, ACT
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41
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Gilbert C. Low risk to certain diseases in aging: role of the autonomic nervous system and calcium metabolism. Mech Ageing Dev 1993; 70:95-113. [PMID: 8231292 DOI: 10.1016/0047-6374(93)90062-v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The low risk of aging Africans, as opposed to high risk of Caucasians, to certain major disorders, including Parkinson's disease, myocardial infarction, osteoporosis and fractures, some rheumatic diseases, and an overall reduced incidence of cancer, has not been explained. In this study it is proposed, firstly, that relative risk is determined by a common physiological mechanism in which ANS status and calcium metabolism play a central role; secondly, that distinctive features of this mechanism in Africans may be subtly increased vagal tone, relatively enhanced dopaminergic versus noradrenergic activity, and an efficient dopamine/vitamin D-parathormone, anabolic hormone regulation of bone metabolism, and cell calcium homeostasis; and thirdly, that the neuroendocrine-metabolic context determines the response to specific stimuli; consequently, 'risk' factors, as defined for particular disorders, are not universally applicable. Maintained dopaminergic activity, as proposed for Africans, coupled with low risk to certain disorders, confirms the experimentally demonstrated paramount importance of this neurotransmitter in retarding aging processes in animals. The neuroendocrine profile as defined for Africans is consistent with a potentially extended period of physical and mental competence and a conceivable shorter duration of involutionary decline.
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Oyama Y, Ueha T, Hayashi A. Effect of tri-n-butyltin on intracellular Ca2+ concentration of rat cerebellar neurons. Eur J Pharmacol 1993; 248:89-93. [PMID: 8339756 DOI: 10.1016/0926-6917(93)90029-p] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of tri-n-butyltin on the intracellular Ca2+ concentration ([Ca2+]i) of cerebellar neurons dissociated from rats was examined using fluo-3 and a flow cytometer. Tri-n-butyltin at 100 nM or more (up to 1 microM) increased the [Ca2+]i in a dose-dependent manner. The effect of tri-n-butyltin on the [Ca2+]i was greatly reduced under external Ca(2+)-free ([Ca2+]o-free) conditions, suggesting its dependence on the presence of [Ca2+]o. Lower trialkyltins, such as triethyltin and trimethyltin at 1 microM, exerted little or no action on the [Ca2+]i. Therefore, the cytotoxic action of tri-n-butyltin may be different from those of lower trialkyltins.
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Affiliation(s)
- Y Oyama
- Department of Health Sciences, Faculty of Integrated Arts and Sciences, University of Tokushima, Japan
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43
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Mertens MJ, Pfaffendorf M, van Zwieten PA. Differential response of hypertrophied rat hearts to various alpha 1-adrenoceptor agonists. Fundam Clin Pharmacol 1993; 7:93-101. [PMID: 8098005 DOI: 10.1111/j.1472-8206.1993.tb00222.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
With respect to the heart, the prolonged existence of hypertension, both in man and in experimental animals is predominantly characterized by an increase in left ventricular myocardial mass. In this process, the autonomic nervous system plays an important role. Although endogenous catecholamine stimulation of the heart is mainly exerted via the beta-adrenoceptors, in several mammalian species, the stimulation of cardiac alpha 1-adrenoceptors also mediates positive inotropic actions. We investigated the functional responses of isolated hypertrophied hearts taken from spontaneously hypertensive rats (SHR) and rats with an induced aortic stenosis (ASR) to various alpha 1-adrenoceptor agonists and compared them with those from age matched Wistar Kyoto (WKY) and "sham" operated controls. Accordingly, we studied the functional response to: methoxamine (alpha 1), cirazoline (alpha 1) and phenylephrine (alpha 1 > beta 1). The inotropic response to the alpha 1-adrenoceptor agonists cirazoline and methoxamine proved to be significantly weaker in hypertrophied hearts from SHR and ASR than in non-hypertrophied hearts from WHY and "sham" operated controls (p < 0.05). The inotropic response to phenylephrine remained intact in hypertrophied myocardial tissue. However, it was significantly reduced when the hearts were pre-treated with the intracellular Ca(2+)-antagonists ryanodine and TMB-8. These findings show that the mechanism of sarcolemmal Ca2+ release, activated by phenylephrine, is still intact in the hypertrophied myocardial cell. In conclusion, these data show that cardiac hypertrophy, be it of genetical or mechanical origin, leads to a reduced response of the isolated heart to alpha 1-adrenoceptor stimulation.
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Affiliation(s)
- M J Mertens
- Department of Pharmacotherapy, Academic Medical Centre, Amsterdam, The Netherlands
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44
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Livingston FR, Lui EM, Loeb GA, Forman HJ. Sublethal oxidant stress induces a reversible increase in intracellular calcium dependent on NAD(P)H oxidation in rat alveolar macrophages. Arch Biochem Biophys 1992; 299:83-91. [PMID: 1444455 DOI: 10.1016/0003-9861(92)90247-t] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A concentration-dependent elevation of intracellular calcium ([Ca2+]i) and oxidation of NAD(P)H occurred in alveolar macrophages during exposure to sublethal tert-butylhydroperoxide concentrations (tBOOH) (< or = 100 microM in 1 ml with 1 x 10(6) cells). Oxidation of NAD(P)H preceded a rise in [Ca2+]i. The elevation of [Ca2+]i was reversible at < 50 microM tBOOH exposure and the return to the steady state [Ca2+]i correlated temporally with repletion of NAD(P)H. At > 50 microM tBOOH, the changes in NAD(P)H and [Ca2+]i were sustained. The relative contributions of NADPH and NADH oxidation were examined by varying the substrates supplying reducing equivalents and by inhibiting glutathione reductase activity. The results suggested that at < 50 microM tBOOH, oxidation of NADPH predominated, while at > 50 microM tBOOH, NADH oxidation predominated. A complex relationship between the relative roles of NADPH and NADH oxidation and the elevation of [Ca2+]i was revealed: (i) reversible oxidation of NADPH is associated with the initial and reversible elevation of [Ca2+]i at < 50 microM tBOOH; (ii) the sustained elevation of [Ca2+]i at > 50 microM tBOOH correlates with the sustained oxidation of NADH; and (iii) the changes in [Ca2+]i did not depend on influx of extracellular Ca2+. We speculate that at low tBOOH, Ca2+ was released from the NADPH/NADP(+)-sensitive mitochondrial Ca2+ pool while higher tBOOH caused additional Ca2+ release from GSH/GSSG-sensitive nonmitochondrial Ca2+ pools with sustained elevation of [Ca2+]i due to decreased mitochondrial Ca2+ reuptake.
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Affiliation(s)
- F R Livingston
- Department of Pediatrics, University of Southern California, Childrens Hospital Los Angeles 90027
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Shibata S, Kodama K, Tominaga K, Ueki S, Watanabe S. Assessment of the role of adrenoceptor function in ischemia-induced impairment of 2-deoxyglucose uptake and CA1 field potential in rat hippocampal slices. Eur J Pharmacol 1992; 221:255-60. [PMID: 1426004 DOI: 10.1016/0014-2999(92)90710-l] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The release of catecholamines, dopamine and noradrenaline has been suggested to play a role in mediating ischemic damage in susceptible brain regions, the hippocampus and striatum. We now provide evidence that suggests a role for adrenoceptors in the deficit of 2-deoxyglucose uptake and CA1 field potential induced in hippocampal slices by hypoxia/hypoglycemia (ischemia). Treatment with alpha 1- or beta-adrenoceptor agonists or cAMP potentiated an ischemia-induced decline of both 2-deoxyglucose uptake and CA1 field potential in hippocampal slices, whereas alpha 1- or beta-adrenoceptor antagonists, or alpha 2-adrenoceptor agonists produced a remarkable neuroprotective action against these deficits. The results indicate that stimulation of adrenoceptors may play a detrimental role in the development of ischemic damage, and suggest a neuroprotective action for adrenoceptor antagonists, which may lessen the functional deficits induced by ischemia.
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Affiliation(s)
- S Shibata
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Ganguly A. Atrial natriuretic peptide-induced inhibition of aldosterone secretion: a quest for mediator(s). Am J Physiol Endocrinol Metab 1992; 263:E181-94. [PMID: 1355332 DOI: 10.1152/ajpendo.1992.263.2.e181] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Atrial natriuretic peptide (ANP) inhibits aldosterone secretion evoked by its physiological secretagogues by a mechanism(s) likely to involve intracellular messengers. When one examines the results of various investigations so far, this premise, although not definitive yet, seems to be supported. Therefore a brief perspective on the cellular messengers of the various secretagogues is provided before the inquiry into the possible mechanism of action of ANP. The receptors of ANP in the adrenal cells have been identified and characterized. ANP inhibits adenylate cyclase in various tissues through an inhibitory G protein, which appears to explain in part the inhibitory effect of ANP on adrenocorticotropin-induced aldosterone secretion. However, there could be other possible effects of ANP as discussed. ANP probably inhibits aldosterone secretion evoked by angiotensin II and potassium by interfering with the appropriate changes in calcium flux and cell calcium concentration, concomitants of stimulation by these secretagogues. The potential modes of these effects are probed. The role of guanosine 3',5'-cyclic monophosphate, which is increased by receptor activation of guanylate cyclase by ANP and is thought to play a major role in the biological effects of ANP in some other tissues, remains controversial in the aldosterone-lowering effect of ANP, and this is also discussed extensively in this review.
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Chikahisa L, Oyama Y. Tri-n-butyltin increases intracellular Ca2+ in mouse thymocytes: a flow-cytometric study using fluorescent dyes for membrane potential and intracellular Ca2+. PHARMACOLOGY & TOXICOLOGY 1992; 71:190-5. [PMID: 1438040 DOI: 10.1111/j.1600-0773.1992.tb00543.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Effects of tri-n-butyltin (TBT) on mouse thymocytes were examined using a flow-cytometer and fluorescent dyes for membrane potential and intracellular Ca2+ ([Ca2+]i). TBT at concentrations from 1 x 10(-7) M to 3 x 10(-7) M caused hyperpolarization in thymocytes during 30 min. after drug application in a time- and dose-dependent manner. Further increase in TBT concentration (to 1 x 10(-6) M) made hyperpolarization of thymocytes more profound within 5 min. after application, thereafter gradually depolarized them during the next 25 min. TBT at 3 x 10(-8) M or more (up to 1 x 10(-6) M) increased the [Ca2+]i of thymocytes. After reaching maximum [Ca2+]i at the various TBT concentrations used within 5 min. after drug application, the [Ca2+]i slightly decreased in a time-dependent manner. Effects of TBT on membrane potential and the [Ca2+]i were greatly reduced under nominal external Ca(2+)-free condition. Results suggest that TBT can promote Ca(2+)-influx to thymocytes, resulting in hyperpolarization by activation of Ca(2+)-dependent K+ current. The increase in [Ca2+]i by TBT may be related to its cytotoxic action on thymocytes.
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Affiliation(s)
- L Chikahisa
- Department of Health Science, Faculty of Integrated Arts and Sciences, University of Tokushima, Japan
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48
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Kröner H. The different routes of calcium efflux from liver mitochondria. BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1992; 373:229-35. [PMID: 1378282 DOI: 10.1515/bchm3.1992.373.1.229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Calcium efflux from liver mitochondria, induced by an uncoupler during incubation at 20 degrees C, is largely inhibited by the prior addition of ruthenium red or EGTA. The inhibition by EGTA (i.e. by chelation of Ca2+) is impaired by the presence of EDTA (i.e. by chelation of Mg2+), and it is completely abolished by addition of spermine. In contrast, the inhibition of calcium efflux at 20 degrees C by ruthenium red is unaffected by EGTA or spermine. This latter pathway of calcium efflux therefore represents the reversal of the calcium uniporter. During incubation at 30 degrees C, uncoupler-induced calcium efflux is incompletely inhibited by ruthenium red, and the residual calcium efflux occurs via membrane transition. The kinetics of this process as well as its exceptionally strong dependence on temperature constitute the main evidence for considering that membrane transition modifies the uniporter, and that the modified uniporter is responsible for the residual calcium efflux. It was shown that the route of ruthenium red-insensitive calcium efflux from energized mitochondria under standard conditions is the same, irrespective of whether the uniporter is running or is blocked by ruthenium red. The development of methods for the clear experimental separation of these different routes of calcium efflux under different conditions is still critically important.
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Affiliation(s)
- H Kröner
- Institut für Physiologische Chemie I, Universität Düsseldorf
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49
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Abstract
Diabetes mellitus and hypertension are common diseases that coexist at a greater frequency than chance alone would predict. Hypertension in the diabetic individual markedly increases the risk and accelerates the course of cardiac disease, peripheral vascular disease, stroke, retinopathy, and nephropathy. Our understanding of the factors that markedly increase the frequency of hypertension in the diabetic individual remains incomplete. Diabetic nephropathy is an important factor involved in the development of hypertension in diabetics, particularly type I patients. However, the etiology of hypertension in the majority of diabetic patients cannot be explained by underlying renal disease and remains "essential" in nature. The hallmark of hypertension in type I and type II diabetics appears to be increased peripheral vascular resistance. Increased exchangeable sodium may also play a role in the pathogenesis of blood pressure in diabetics. There is increasing evidence that insulin resistance/hyperinsulinemia may play a key role in the pathogenesis of hypertension in both subtle and overt abnormalities of carbohydrate metabolism. Population studies suggest that elevated insulin levels, which often occurs in type II diabetes mellitus, is an independent risk factor for cardiovascular disease. Other cardiovascular risk factors in diabetic individuals include abnormalities of lipid metabolism, platelet function, and clotting factors. The goal of antihypertensive therapy in the patient with coexistent diabetes is to reduce the inordinate cardiovascular risk as well as lowering blood pressure.
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Affiliation(s)
- M Epstein
- Medical Services, Department of Veterans Affairs Medical Center, Miami, FL 33125
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Triphenyltin-Induced Increase in the Intracellular Ca2+of Dissociated Mammalian CNS Neuron: Its Independence from Voltage-Dependent Ca2+Channels. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0021-5198(19)39728-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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