Calcium in Biology - wikipedia Calcium in Biology Calcium ions ( Ca ) play a vital role in the physiology and biochemistry of organisms and the cell. They play an important role in signal transduction pathways, where they act as a second messenger, in neurotransmitter release from neurons, in contraction of all muscle cell types, and in fertilization. Many enzymes require calcium ions as a cofactor, those of the blood - clotting cascade being notable examples. Extracellular calcium is also important for maintaining the potential difference across excitable cell membranes, as well as proper bone formation. Calcium levels in mammals are tightly regulated, with bone acting as the major mineral storage site. Calcium ions, Ca, are released from bone into the bloodstream under controlled conditions. Calcium is transported through the bloodstream as dissolved ions or bound to proteins such as serum albumin. Parathyroid hormone secreted by the parathyroid gland regulates the resorption of Ca from bone, reabsorption in the kidney back into circulation, and increases in the activation of vitamin D to calcitriol. Calcitriol, the active form of vitamin D, promotes absorption of calcium from the intestines and the mobilization of calcium ions from bone matrix. Calcitonin secreted from the parafollicular cells of the thyroid gland also affects calcium levels by opposing parathyroid hormone ; however, its physiological significance in humans is dubious. Calcium storages are intracellular organelles, that constantly accumulate Ca ions and release them during certain cellular events. Intracellular Ca storages include mitochondria and the endoplasmic reticulum. Characteristic concentrations of calcium in model organisms are : in E. coli 3mM ( bound ), 100nM ( free ), in budding yeast 2mM ( bound ), in mammalian cell 10 - 100nM ( free ) and in blood plasma 2mM. Contents 1 Animals 1.1 Vertebrates 1.1. 1 Effects 1.1. 2 Adaptation 1.1. 3 Negative effects and pathology 1.2 Invertebrates 2 Plants 2.1 Stomata closing 2.2 Cellular division 2.3 Structural roles 2.4 Cell signaling 3 Humans 3.1 Dietary recommendations 3.2 Food sources 3.3 Measurement in blood 3.3. 1 Corrected calcium 4 See also 5 References 6 External links Animals Vertebrates Main article : Calcium metabolism In vertebrates, calcium ions, like many other ions, are of such vital importance to many physiological processes that its concentration is maintained within specific limits to ensure adequate homeostasis. This is evidenced by human plasma calcium, which is one of the most closely regulated physiological variables in the human body. Normal plasma levels vary between 1 and 2 % over any given time. Approximately half of all ionized calcium circulates in its unbound form, with the other half being complexed with plasma proteins such as albumin, as well as anions including bicarbonate, citrate, phosphate, and sulfate. Calcium regulation in the human body. Different tissues contain calcium in different concentrations. For instance, Ca ( mostly calcium phosphate and some calcium sulfate ) is the most important ( and specific ) element of bone and calcified cartilage. In humans, the total body content of calcium is present mostly in the form of bone mineral ( roughly 99 % ). In this state, it is largely unavailable for exchange / bioavailability. The way to overcome this is through the process of bone resorption, in which calcium is liberated into the bloodstream through the action of bone osteoclasts. The remainder of calcium is present within the extracellular and intracellular fluids. Within a typical cell, the intracellular concentration of ionized calcium is roughly 100 nM, but is subject to increases of 10 -- to 100-fold during various cellular functions. The intracellular calcium level is kept relatively low with respect to the extracellular fluid, by an approximate magnitude of 12,000-fold. This gradient is maintained through various plasma membrane calcium pumps that utilize ATP for energy, as well as a sizable storage within intracellular compartments. In electrically excitable cells, such as skeletal and cardiac muscles and neurons, membrane depolarization leads to a Ca transient with cytosolic Ca concentration reaching 400 nM and above. Mitochondria are capable of sequestering and storing some of that Ca. It has been estimated that mitochondrial matrix free calcium concentration rises to the tens of micromolar levels in situ during neuronal activity. Effects The effects of calcium on human cells are specific, meaning that different types of cells respond in different ways. However, in certain circumstances, its action may be more general. Ca ions are one of the most widespread second messengers used in signal transduction. They make their entrance into the cytoplasm either from outside the cell through the cell membrane via calcium channels ( such as calcium - binding proteins or voltage - gated calcium channels ), or from some internal calcium storages such as the endoplasmic reticulum and mitochondria. Levels of intracellular calcium are regulated by transport proteins that remove it from the cell. For example, the sodium - calcium exchanger uses energy from the electrochemical gradient of sodium by coupling the influx of sodium into cell ( and down its concentration gradient ) with the transport of calcium out of the cell. In addition, the plasma membrane Ca ATPase ( PMCA ) obtains energy to pump calcium out of the cell by hydrolysing adenosine triphosphate ( ATP ). In neurons, voltage - dependent, calcium - selective ion channels are important for synaptic transmission through the release of neurotransmitters into the synaptic cleft by vesicle fusion of synaptic vesicles. Calcium 's function in muscle contraction was found as early as 1882 by Ringer. Subsequent investigations were to reveal its role as a messenger about a century later. Because its action is interconnected with cAMP, they are called synarchic messengers. Calcium can bind to several different calcium - modulated proteins such as troponin - C ( the first one to be identified ) and calmodulin, proteins that are necessary for promoting contraction in muscle. In the endothelial cells which line the inside of blood vessels, Ca ions can regulate several signaling pathways which cause the smooth muscle surrounding blood vessels to relax. Some of these Ca - activated pathways include the stimulation of eNOS to produce nitric oxide, as well as the stimulation of K channels to efflux K and cause hyperpolarization of the cell membrane. Both nitric oxide and hyperpolarization cause the smooth muscle to relax in order to regulate the amount of tone in blood vessels. However, dysfunction within these Ca - activated pathways can lead to an increase in tone caused by unregulated smooth muscle contraction. This type of dysfunction can be seen in cardiovascular diseases, hypertension, and diabetes. Adaptation Ca ion flow regulate several secondary messenger systems in neural adaptation for visual, auditory, and the olfactory system. It may often be bound to calmodulin such as in the olfactory system to either enhance or repress cation channels. Other times the calcium level change can actually release guanylyl cyclase from inhibition, like in the photoreception system Ca ion can also determine the speed of adaptation in a neural system depending on the receptors and proteins that have varied affinity for detecting levels of calcium to open or close channels at high concentration and low concentration of calcium in the cell at that time. Cell type Effect endothelial cells ↑ vasodilation secretory cells ( mostly ) ↑ secretion ( vesicle fusion ) juxtaglomerular cell ↓ secretion Parathyroid chief cells ↓ secretion Neurons transmission ( vesicle fusion ), Neural adaptation T cells Activation in response to antigen presentation to the T cell receptor myocytes contraction Activation of protein kinase C Various Activation of protein kinase C Further reading : Function of protein kinase C Reference ranges for blood tests, showing calcium levels in purple at right. Negative effects and pathology Substantial decreases in extracellular Ca ion concentrations may result in a condition known as hypocalcemic tetany, which is marked by spontaneous motor neuron discharge. In addition, severe hypocalcaemia will begin to affect aspects of blood coagulation and signal transduction. Ca ions can damage cells if they enter in excessive numbers ( for example, in the case of excitotoxicity, or over-excitation of neural circuits, which can occur in neurodegenerative diseases, or after insults such as brain trauma or stroke ). Excessive entry of calcium into a cell may damage it or even cause it to undergo apoptosis, or death by necrosis. Calcium also acts as one of the primary regulators of osmotic stress ( Osmotic shock ). Chronically elevated plasma calcium ( hypercalcemia ) is associated with cardiac arrhythmias and decreased neuromuscular excitability. One cause of hypercalcemia is a condition known as hyperparathyroidism. Invertebrates Some invertebrates use calcium compounds for building their exoskeleton ( shells and carapaces ) or endoskeleton ( echinoderm plates and poriferan calcareous spicules ). Plants Stomata closing When abscisic acid signals the guard cells, free Ca ions enter the cytosol from both outside the cell and internal stores, reversing the concentration gradient so the K+ ions begin exiting the cell. The loss of solutes makes the cell flaccid and closes the stomatal pores. Cellular division Calcium is a necessary ion in the formation of the mitotic spindle. Without the mitotic spindle, cellular division can not occur. Although young leaves have a higher need for calcium, older leaves contain higher amounts of calcium because calcium is relatively immobile through the plant. It is not transported through the phloem because it can bind with other nutrient ions and precipitate out of liquid solutions. Structural roles Ca ions are an essential component of plant cell walls and cell membranes, and are used as cations to balance organic anions in the plant vacuole. The Ca concentration of the vacuole may reach millimolar levels. The most striking use of Ca ions as a structural element in algae occurs in the marine coccolithophores, which use Ca to form the calcium carbonate plates, with which they are covered. Calcium is needed to form the pectin in the middle lamella of newly formed cells. Calcium is needed to stabilize the permeability of cell membranes. Without calcium, the cell walls are unable to stabilize and hold their contents. This is particularly important in developing fruits. Without calcium, the cell walls are weak and unable to hold the contents of the fruit. Some plants accumulate Ca in their tissues, thus making them more firm. Calcium is stored as Ca - oxalate crystals in plastids. Calcium coordination plays an important role in defining the structure and function of proteins. An example a protein with calcium coordination is von Willebrand factor ( vWF ) which has an essential role in blood clot formation process. It is discovered - using single molecule optical tweezers measurement -- that calcium - bound vWF acts as a shear force sensor in the blood. Shear force leads to unfolding of the A2 domain of vWF whose refolding rate is dramatically enhanced in the presence of calcium. Cell signaling Ca ions are usually kept at nanomolar levels in the cytosol of plant cells, and act in a number of signal transduction pathways as second messengers. Humans Age - adjusted daily calcium recommendations ( from U.S. Institute of Medicine RDAs ) Age Calcium ( mg / day ) 1 - 3 years 700 4 - 8 years 1000 9 - 18 years 1300 19 - 50 years 1000 > 51 years 1000 Pregnancy 1000 Lactation 1000 Dietary recommendations The U.S. Institute of Medicine ( IOM ) established Recommended Dietary Allowances ( RDAs ) for calcium in 1997 and updated those values in 2011. See table. The European Food Safety Authority ( EFSA ) uses the term Population Reference Intake ( PRIs ) instead of RDAs and sets slightly different numbers : ages 4 - 10 800 mg, ages 11 - 17 1150 mg, ages 18 - 24 1000 mg, and > 25 years 950 mg. Because of concerns of long - term adverse side effects such as calcification of arteries and kidney stones, the IOM and EFSA both set Tolerable Upper Intake Levels ( ULs ) for the combination of dietary and supplemental calcium. From the IOM, people ages 9 - 18 years are not supposed to exceed 3,000 mg / day ; for ages 19 - 50 not to exceed 2,500 mg / day ; for ages 51 and older, not to exceed 2,000 mg / day. The EFSA set UL at 2,500 mg / day for adults but decided the information for children and adolescents was not sufficient to determine ULs. For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value ( % DV ). For calcium labeling purposes 100 % of the Daily Value was 1000 mg, but as of May 27, 2016 it was revised to 1300 mg to bring it into agreement with the RDA. A table of the old and new adult Daily Values is provided at Reference Daily Intake. The original deadline to be in compliance was July 28, 2018, but on September 29, 2017 the FDA released a proposed rule that extended the deadline to January 1, 2020 for large companies and January 1, 2021 for small companies... Food sources The United States Department of Agriculture ( USDA ) web site has a very complete searchable table of calcium content ( in milligrams ) in foods, per common measures such as per 100 grams or per a normal serving ( https://ndb.nal.usda.gov/ndb/ ). Calcium amount in foods, per 100 grams : parmesan ( cheese ) = 1140 mg milk powder = 909 mg goat hard cheese = 895 mg Cheddar cheese = 720 mg tahini paste = 427 mg molasses = 273 mg almonds = 234 mg goat milk = 134 mg sesame seeds ( unhulled ) = 125 mg nonfat cow milk = 122 mg plain whole - milk yogurt = 121 mg hazelnuts = 114 mg ricotta ( skimmed milk cheese ) = 90 mg brown sugar = 85 mg lentils = 79 mg wheat germs = 72 mg pigeon peas = 62.7 mg chickpeas = 53.1 eggs, boiled = 50 mg flour = 41 mg orange = 40 mg human milk = 33 mg rice, white, long - grain, parboiled, enriched, cooked = 19 mg trout = 19 mg beef = 12 mg cod = 11 mg Measurement in blood The amount of calcium in blood ( more specifically, in blood plasma ) can be measured as total calcium, which includes both protein - bound and free calcium. In contrast, ionized calcium is a measure of free calcium. An abnormally high level of calcium in plasma is termed hypercalcemia and an abnormally low level is termed hypocalcemia, with `` abnormal '' generally referring to levels outside the reference range. Reference ranges for blood tests for calcium Target Lower limit Upper limit Unit Ionized calcium 1.03, 1.10 1.23, 1.30 mmol / L 4.1, 4.4 4.9, 5.2 mg / dL Total calcium 2.1, 2.2 2.5, 2.6, 2.8 mmol / L 8.4, 8.5 10.2, 10.5 mg / dL The main methods to measure serum calcium are : O - Cresolphalein Complexone Method ; A disadvantage of this method is that the volatile nature of the 2 - Amino - 2 - Methyl - 1 - Propanol used in this method makes it necessary to calibrate the method every few hours in a clinical laboratory setup. Arsenazo III Method ; This method is more robust, but the arsenic in the reagent is a health hazard. The total amount of Ca present in a tissue may be measured using Atomic absorption spectroscopy, in which the tissue is vaporized and combusted. To measure Ca concentration or spatial distribution within the cell cytoplasm in vivo, a range of fluorescent reporters may be used. These include cell permeable, calcium - binding fluorescent dyes such as Fura - 2 or genetically engineered variant of green fluorescent protein ( GFP ) named Cameleon. Corrected calcium As access to an ionized calcium is not always available a corrected calcium may be used instead. To calculate a corrected calcium in mmo / l one takes the total calcium in mmol / L and adds it to ( ( 40 minus the serum albumin in g / L ) multiplied by 0.2 ). See also Bone seeker References ^ Jump up to : Brini, Marisa ; Ottolini, Denis ; Calì, Tito ; Carafoli, Ernesto ( 2013 ). `` Chapter 4. Calcium in Health and Disease ''. In Astrid Sigel, Helmut Sigel and Roland K.O. Sigel. Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences. 13. Springer. pp. 81 -- 137. doi : 10.1007 / 978 - 94 - 007 - 7500 - 8_4. ^ Jump up to : Brini, Marisa ; Call, Tito ; Ottolini, Denis ; Carafoli, Ernesto ( 2013 ). `` Chapter 5 Intracellular Calcium Homeostasis and Signaling ''. In Banci, Lucia ( Ed. ). Metallomics and the Cell. Metal Ions in Life Sciences. 12. Springer. doi : 10.1007 / 978 - 94 - 007 - 5561 - 1_5. ISBN 978 - 94 - 007 - 5560 - 4. CS1 maint : Extra text : editors list ( link ) electronic - book ISBN 978 - 94 - 007 - 5561 - 1 ISSN 1559 - 0836 electronic - ISSN 1868 - 0402 ^ Jump up to : Wilson, C.H. ; Ali, E.S. ; Scrimgeour, N. ; Martin, A.M. ; Hua, J. ; Tallis, G.A. ; Rychkov, G.Y. ; Barritt, G.J. ( 2015 ). `` Steatosis inhibits liver cell store - operated Ca ( 2 ) ( + ) entry and reduces ER Ca ( 2 ) ( + ) through a protein kinase C - dependent mechanism ''. Biochem J. 466 ( 2 ) : 379 -- 390. doi : 10.1042 / bj20140881. PMID 25422863. Jump up ^ Milo, Ron ; Philips, Rob. `` Cell Biology by the Numbers : What are the concentrations of different ions in cells ? ''. book.bionumbers.org. Retrieved 24 March 2017. Jump up ^ Brini, Marisa ; Ottolini, Denis ; Calì, Tito ; Carafoli, Ernesto ( 2013 ). `` Chapter 4. Calcium in Health and Disease ''. In Astrid Sigel, Helmut Sigel and Roland K.O. Sigel. Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences. 13. Springer. pp. 81 -- 138. doi : 10.1007 / 978 - 94 - 007 - 7500 - 8_4. Jump up ^ Boron, Walter F. ; Boulpaep, Emile L ( 2003 ). `` The Parathyroid Glands and Vitamin D ''. Medical Physiology : A Cellular And Molecular Approach. Elsevier / Saunders. p. 1094. ISBN 1 - 4160 - 2328 - 3. Jump up ^ Ivannikov, M. ; et al. ( 2013 ). `` Mitochondrial Free Ca Levels and Their Effects on Energy Metabolism in Drosophila Motor Nerve Terminals ''. Biophys. J. 104 ( 11 ) : 2353 -- 2361. doi : 10.1016 / j. bpj. 2013.03. 064. PMC 3672877. PMID 23746507. Jump up ^ Christopher J Garland, C Robin Hiley, Kim A Dora. EDHF : spreading the influence of the endothelium. British Journal of Pharmacology. 164 : 3, 839 - 852. ( 2011 ). Jump up ^ Hua Cai, David G. Harrison. Endothelial Dysfunction in Cardiovascular Diseases : The Role of Oxidant Stress. Circulation Research. 87, 840 - 844. ( 2000 ). Jump up ^ Dougherty, D.P. ; Wright, G.A. ; Yew, A.C. ( 2005 ). `` Computational model of the cAMP - mediated sensory response and calcium - dependent adaptation in vertebrate olfactory receptor neurons ''. Proceedings of the National Academy of Sciences. 102 ( 30 ) : 10415 -- 20. doi : 10.1073 / pnas. 0504099102. PMC 1180786. PMID 16027364. Jump up ^ Pugh Jr, E.N. ; Lamb, T.D. ( 1990 ). `` Cyclic GMP and calcium : The internal messengers of excitation and adaptation in vertebrate photoreceptors ''. Vision research. 30 ( 12 ) : 1923 -- 48. PMID 1962979. Jump up ^ Gillespie, P.G. ; Cyr, J.L. ( 2004 ). `` Myosin - 1c, the hair cell 's adaptation motor ''. Annual Review of Physiology. 66 : 521 -- 45. doi : 10.1146 / annurev. physiol. 66.032102. 112842. PMID 14977412. ^ Jump up to : Boron, Walter F. ; Boulpaep, Emile L ( 2003 ). Medical Physiology : A Cellular And Molecular Approach. Elsevier / Saunders. p. 867. ISBN 1 - 4160 - 2328 - 3. Jump up ^ Levinson, Warren ( 2008 ). Review of medical microbiology and immunology. McGraw - Hill Medical. p. 414. ISBN 0 - 07 - 149620 - 3. Jump up ^ White, Philip J. ; Martin R. Broadley ( 2003 ). `` Calcium in Plants ''. Annals of Botany. 92 ( 4 ) : 487 -- 511. doi : 10.1093 / aob / mcg164. PMID 12933363. Jump up ^ Jakobi AJ, Mashaghi A, Tans SJ, Huizinga EG. Calcium modulates force sensing by the von Willebrand factor A2 domain. Nature Commun. 2011 Jul 12 ; 2 : 385. ( 1 ) ^ Jump up to : Dietary Reference Intakes for Calcium and Vitamin D, Chapter 5 Dietary Reference Intakes pages 345 - 402. Washington, D.C : National Academies Press. 2011. ISBN 0 - 309 - 16394 - 3. Jump up ^ `` Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies '' ( PDF ). 2017. Jump up ^ Dietary Reference Intakes for Calcium and Vitamin D, Chapter 6 Tolerable Upper Intake Levels pages 403 - 456. Washington, D.C : National Academies Press. 2011. ISBN 0 - 309 - 16394 - 3. Jump up ^ Tolerable Upper Intake Levels For Vitamins And Minerals ( PDF ), European Food Safety Authority, 2006 Jump up ^ `` Federal Register May 27, 2016 Food Labeling : Revision of the Nutrition and Supplement Facts Labels. FR page 33982 '' ( PDF ). Jump up ^ `` Changes to the Nutrition Facts Panel - Compliance Date '' ^ Jump up to : Larsson L, Ohman S ( November 1978 ). `` Serum ionized calcium and corrected total calcium in borderline hyperparathyroidism ''. Clin. Chem. 24 ( 11 ) : 1962 -- 5. PMID 709830. ^ Jump up to : Reference range list from Uppsala University Hospital ( `` Laborationslista '' ). Artnr 40284 Sj74a. Issued on April 22, 2008 ^ Jump up to : Derived from molar values using molar mass of 40.08 g mol − 1 ^ Jump up to : Last page of Deepak A. Rao ; Le, Tao ; Bhushan, Vikas ( 2007 ). First Aid for the USMLE Step 1 2008 ( First Aid for the Usmle Step 1 ). McGraw - Hill Medical. ISBN 0 - 07 - 149868 - 0. ^ Jump up to : Derived from mass values using molar mass of 40.08 g mol − 1 ^ Jump up to : Blood Test Results -- Normal Ranges Bloodbook.Com Jump up ^ Clin Chem. 1992 Jun ; 38 ( 6 ) : 904 - 8. Single stable reagent ( Arsenazo III ) for optically robust measurement of calcium in serum and plasma. Leary NO, Pembroke A, Duggan PF. Jump up ^ Minisola, S ; Pepe, J ; Piemonte, S ; Cipriani, C ( 2 June 2015 ). `` The diagnosis and management of hypercalcaemia ''. BMJ ( Clinical research ed. ). 350 : h2723. doi : 10.1136 / bmj. h2723. PMID 26037642. External links USDA national nutritional database, Calcium content of selected foods Calcium and vitamin D. Reference ranges for blood tests ( CPT 82000 -- 84999 ) Electrolytes Sodium Potassium Chloride Calcium Renal function Creatinine Urea BUN - to - creatinine ratio Plasma osmolality Serum osmolal gap Acid - base Anion gap Arterial blood gas Base excess Bicarbonate CO content Iron tests Ferritin Serum iron Transferrin saturation Total iron - binding capacity Transferrin Transferrin receptor Hormones ACTH stimulation test Thyroid function tests Thyroid - stimulating hormone Metabolism Blood lipids Cardiovascular Cardiac marker Troponin test CPK - MB test Lactate dehydrogenase Myoglobin Glycogen phosphorylase isoenzyme BB Liver function tests Proteins Human serum albumin Serum total protein ALP transaminases ALT AST AST / ALT ratio Bilirubin Unconjugated Conjugated Pancreas Amylase Lipase Pancreatic lipase Nitric oxide signaling modulators Forms Nitroxyl anion ( NO ; oxonitrate ( 1 - ), hyponitrite anion ) Nitric oxide ( NO ; nitrogen monoxide ) Nitrosonium ( NO ; nitrosyl cation ) Targets sGC Activators : Cinaciguat ( BAY 58 - 2667 ) Riociguat ( BAY 63 - 2521 ) Inhibitors : ODQ NO donors ( prodrugs ) Nitrates : Diethylene glycol dinitrate ( DEGDN ) Erythritol tetranitrate ( ETN ) Ethylene glycol dinitrate ( EGDN ; nitroglycol ) Isosorbide mononitrate ( ISMN ) Isosorbide dinitrate ( ISDN ) Itramin tosilate Mannitol hexanitrate Naproxcinod ( nitronaproxen ; AZD - 3582, HCT - 3012 ) NCX - 466 NCX - 2216 NCX - 4016 NCX 4040 NCX - 4215 Nicorandil Nipradilol ( K - 351 ) Nitrate ( NO − 3 ) Nitroatorvastatin ( NCX - 6560 ) Nitroflurbiprofen ( HCT - 1026 ) Nitrofluvastatin Nitroglycerin ( glyceryl trinitrate ( GTN ) ) Nitropravastatin ( NCX - 6550 ) Pentaerithrityl tetranitrate ( PETN ) Propatylnitrate Propylene glycol dinitrate ( PGDN ) Sodium trioxodinitrate ( Angeli 's salt ) Tenitramine Trolnitrate Nitroso compounds / nitrites : Nitrite ( NO − 2 ) ; O - Nitroso compounds ( alkyl nitrites ) : Amyl nitrite ( isoamyl nitrite, isopentyl nitrite ) Cyclohexyl nitrite Ethyl nitrite Hexyl nitrite Isobutyl nitrite ( 2 - methylpropyl nitrite ) Isopropyl nitrite Methyl nitrite n - Butyl nitrite Pentyl nitrite tert - Butyl nitrite ; S - Nitroso compounds ( thionitrites ) : LA810 S - Nitrosoalbumin ( SNALB ) S - Nitrosated AR545C S - Nitroso - N - acetylcysteine ( SNAC ) S - Nitroso - N - acetylpenicillamine ( SNAP ) S - Nitroso - N - valerylpenicillamine ( SNVP ) S - Nitrosocaptopril ( SNO - Cap ) S - Nitrosocysteine ( SNC, CysNO, SNO - Cys ) S - Nitrosodiclofenac S - Nitrosoglutathione ( GSNO, SNOG ) SNO - t - PA SNO - vWF ; N - Nitroso compounds ( e.g., nitrosamines ) : SIN - 1A Nitrosyl compounds : Metal nitrosyl complexes : Roussin 's black salt Roussin 's red salt Sodium nitroprusside ( SNP ) NONOates ( diazeniumdiolates ) : Diethylamine / NO ( DEA / NO ) Diethylenetriamine / NO ( DETA / NO ) GLO / NO JS - K Methylamine hexamethylene methylamine / NO ( MAHMA / NO ) PROLI / NO Spermine / NO ( SPER / NO ) V - PYRRO / NO Heterocyclic compounds : Furoxans : Furoxan REC15 / 2739 ; Sydnonimines : Feprosidnine Linsidomine ( SIN - 1 ) Molsidomine ( SIN - 10 ) Sydnonimine Unsorted : CXL - 1427 FK - 409 FR144220 FR146881 N - Acetyl - N - acetoxy - 4 - chlorobenzenesulfonamide Enzyme ( inhibitors ) NOS nNOS 3 - Bromo - 7 - nitroindazole 3 - Chloroindazole 3 - Chloro - 5 - nitroindazole 5 - Nitroindazole 6 - Nitroindazole 7 - Nitroindazole A-84643 Aminoguanidine ( pimagedine ) ARL - 17477 Indazole N - ( 1 - Iminoethyl ) - L - ornithine ( L - NIO ) N - Methyl - L - arginine ( L - NMA ) N - Propyl - L - arginine ( L - NPA ) Nitroarginine ( NNA, NOARG ) Pentamidine isethionate TRIM iNOS 1 - Amino - 2 - hydroxyguanidine 2 - Ethylaminoguanidine 2 - Iminopiperidine 1400W AEITU Aminoguanidine ( pimagedine ) AMT AR - C 102222 BYK - 191023 Canavanine Cindunistat ( SD - 6010 ) EITU IPTU MITU N - ( 1 - Iminoethyl ) - L - ornithine ( L - NIO ) N - ( 1 - Iminoethyl ) - L - lysine ( L - NIL ) N - Methyl - L - arginine ( L - NMA ) Ronopterin ( VAS - 203 ) TRIM eNOS Aminoguanidine ( pimagedine ) N - ( 1 - Iminoethyl ) - L - ornithine ( L - NIO ) N - Methyl - L - arginine ( L - NMA ) Nitroarginine ( NNA, NOARG ) Unsorted Asymmetric dimethylarginine ( ADMA ) CKD - 712 Guanidinoethyldisulfide ( GED ) GW - 273629 Indospicine KD - 7040 Nitroarginine methyl ester ( NAME ) NCX - 456 NXN - 462 ONO - 1714 VAS - 2381 Arginase ABH N - Hydroxy - L - arginine ( NOHA ) CAMK Calmidazolium W - 7 Others Precursors : L - Arginine N - Hydroxy - L - arginine ( NOHA ) Cofactors : NADPH FAD FMN Heme BH CaM Ca Indirect / downstream NO modulators : ACE inhibitors / AT - II receptor antagonists ( e.g., captopril, losartan ) ET receptor antagonists ( e.g., bosentan ) L - Type calcium channel blockers ( e.g., dihydropyridines : nifedipine ) Nebivolol ( beta blocker ) PDE5 inhibitors ( e.g., sildenafil ) Statins ( e.g., simvastatin ) See also : Receptor / signaling modulators Retrieved from `` https://en.wikipedia.org/w/index.php?title=Calcium_in_biology&oldid=808899334 '' Categories : Signal transduction Calcium Calcium signaling Biology and pharmacology of chemical elements Hidden categories : CS1 maint : Extra text : editors list All articles with unsourced statements Articles with unsourced statements from January 2016 Talk Contents About Wikipedia Русский Српски / srpski Srpskohrvatski / српскохрватски ไทย Українська Tiếng Việt 中文 Edit links This page was last edited on 5 November 2017, at 22 : 14. 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Question: where are calcium ions stored in a cell
Answer: mitochondria