Calcium ionic

The oceans contain vast quantities of ionic calcium,, to the extent of 400 mg/L of seawater (3). Calcium is present ia living organisms as a constituent of bones, teeth, shell, and coral. It is essential to plant as well as animal life. 

In fishes, additive or more-than-additive toxicity occurs with mixtures of salts of copper and mercury, copper-zinc-phenol, and copper-nickel-zinc (Birge and Black 1979). Accumulation of copper in gills of fathead minnows during exposure to 16 pg Cu/L is reduced by added ionic calcium, which competes with Cu for gill binding sites (Playle et al. 1992). 

When ionic or free urinary calcium was evaluated, high protein meals resulted in equal or slightly depressed calciuric response. The levels of ionic calcium in the urine, as determined by a calcium ion-selective electrode, suggest that a considerable amount of urinary calcium was complexed to anions or compounds with anionic groups. 

This Group IIA (or Group 2) element (atomic symbol, Ca atomic number, 20 atomic weight, 40.078 electronic configuration = ls 2s 2p 3s 3p 4s ) loses both As electrons to form a divalent cation of 0.99A ionic radius. Ionic calcium combines readily with oxygen ligands (chiefly water, phosphates, polyphosphates, and carbox-ylates) to form stable metal ion complexes. Ca under-... 

The milk protein casein is a well-known self-assembling food protein (see section 1.1 in chapter six for further details). Semo and coworkers (2007) have demonstrated that casein-based nanoparticles reassembled from sodium caseinate and ionic calcium can provide partial protection... 

Dickinson, E., Davies, E. (1999). Influence of ionic calcium on stability of sodium caseinate emulsions. Colloids and Surfaces B Biointerfaces, 12, 203-212. 

Eliot, C., Radford, S.J., Dickinson E. (2003). Effect of ionic calcium on the flocculation and gelation of sodium caseinate oil-in-water emulsions. In Dickinson, E., van Vliet, T. 

Matia-Merino, L., Lau, K., Dickinson, E. (2004). Effects of low-methoxyl amidated pectin and ionic calcium on rheology and micro structure of acid-induced sodium caseinate gels. Food Hydrocolloids, 18, 271-281. 

Mechanism of Action Modulate influx of ionic calcium across the cell membrane of arterial smooth muscle as well as in conductile and contractile myocardial cells ... 

For nearly half a century the elastic fibre has been considered a primary site of vascular calcification326, 334 336), Calcium deposits in the arterial wall commonly take the form of phosphate salts which are intimately intermeshed with the protein of the elastic fibre327. Much effort has been directed toward identifying the mechanism for the initiation of focal calcification. It has been proposed that the initial step is ionic calcium binding to the uncharged peptide carbonyl oxygens of the elastic fibre protein328, 329. ... 

The bioavailability of calcium from dairy foods is considered to be excellent (Schaafsma 1983). Evidence from animal studies suggests that the form of calcium in dairy foods may influence the bioavailability of this mineral (Wong and LaCroix 1980). For example, dairy foods that contain colloidal calcium phosphate or calcium caseinate (e.g., as in Cheddar cheese) appear to be somewhat better sources of calcium than foods that contain ionic calcium (e.g., yogurt, buttermilk). However, calcium in milk and other milk products is of greater bioavailability to humans than calcium found in other food sources. According to Renner (1983), calcium utilization from skim milk powder is 85% compared with 22-74% from vegetables. Dietary fiber in plant cell... 

One of the early responses made by many types of cells to a stimulus is a rapid influx of calcium ions across the plasma membrane and a resulting increase in the cytoplasmic level of free ionic calcium. 

Menon, G.K., Grayson, S., and Elias, P.M., Ionic calcium reservoirs in mammalian epidermis ultrastructural localization by ion-capture cytochemistry, J. Invest. Dermatol. 84, 508-512,1985. 

Relaxation of the muscle is brought about by removal of the ionic calcium from the sarcoplasm. This calcium is transported across the membrane of the sarcoplasmic reticulum, in an energy requiring process. In addition to the calcium pumping ATPase, the sarcoplasmic reticulum also contains a calcium binding protein called calsequestrin (Section 4.3.3). Some of the calcium segregated by the sarcoplasmic reticulum is apparently bound to this protein within the lumen of the sarcoplasmic reticulum. As sequestration of calcium ions into sarcoplasmic reticulum proceeds, more calcium ions dissociate from their binding sites on troponin C, re-... 

The mitochondrial Ca2+ pool plays a second role in cellular Ca2+ homeostasis by serving as a sink for Ca2+ during times of excessive Ca2+ uptake by the cell. Under this circumstance, the non-ionic calcium pool in the matrix space can increase 10-fold or more, thereby protecting the cell from Ca2+ intoxication. This mechanism provides a temporary device by which the cell can protect itself, but in the long term only by regulating Ca2+ fluxes across the plasma membrane can the cell maintain Ca2+ homeostasis [14]. 

The secretion of all pituitary hormones requires extracellular ionic calcium (Ca2+) and many investigations have shown that stimulation of secretion requires an increase of the concentration of free Ca2+ in the cytoplasm ([Ca2+],). 

The new process includes an upstream nanofiltration twofold pre-concentration step. Thereafter, the regular process including an UF concentration step to achieve the final dry matter value follows. In this case, however, the calcium losses into the serum are much lower as compared to the conventional process, because the final concentration step only has to remove a small amount of serum including the ionic calcium. The final UF step, that is, a partial calcium removal is still necessary to prevent the product to assume a bitter taste during shelf-life. 

In the case of trace analysis of °Sr (e.g., in natural water samples), carriers, most often ionic species such as Sr", Ba", Ca", and Ee" should be used [39]. Ionic calcium is very similar to ionic strontium and should be removed from samples on the basis of differences between the solubility of calcium and strontium nitrates in... 

Exogenous activation is initiated by tissue thromboplastin (= tissue factor) and the activated form of factor XII in the plasma. This complex is enlarged by ionic calcium and platelet factor 3. As a result, the activation of factors IX to IXa and X to Xa is triggered, thus forming a cross-connection between the endogenous and the exogenous system, (s. fig. 19.1)... 

Lll. Li, T. K., and Piechocki, J. T., Determination of serum ionic calcium with an ion-selective electrode evaluation of methodology and normal values. Clin. Chem. 17, 411-416 (1971). 

Like all caldum channel blodcers, verapamil modulates ionic calcium influx across cell membranes of conductile and contractile myocardial cells, as well as arterial smooth muscle. The modulation of calcium influx slows atrioventricular conduction, reduces myocardial contractility and systemic vascular resistance, and results in coronary and peripheral vaso dilation. Verapamil is currently indicated for controlling angina, hypertension, paroxysmal supraventricular tachycardia, and rapid ventricular atrial flutter or fibrillation (1-5),... 

Calcium is one of the most common elements on earth. Most calcium involved in biological systems occurs as hydroxyapatite. a sialic, stabilizing structure like that found in bone. The remaining calcium is ionic (Ca ). Ionic calcium functions as a biochemical regulator, more often within the cell. The importance of calcium ions to physiological functions was realiz.ed first by Ringer, who observed in 1883 the role of Ca in cardiac contracliiity. 

The concentration of (EDTA) ", and thus the ability to complex metal ions, will depend upon the pH. A decrease in pH results in an increase in the deprotonation of EDTA and hence an increase in the concentration of the ED I A ion. The effect of this is that only metal ions with a very high affinity for EDTA will be able to form stable complexes. The stability constants for the EDTA and [diethylenetriaminepentaacetic acid] - (DTPA ) complexes with some important metal ions that are of particular interest for chelation therapy are listed in Table 7.3. It is important to note that the stability of the EDTA and DTPA complexes with toxic metals, such as lead, mercury, cadmium, or plutonium are quite similar to those with essential metals such as zinc, cobalt or copper however, the Ca complex is many orders of magnitude lower. This has important implications for chelation therapy. First, the mobilization and excretion of zinc and other essential metals are likely to be increased, along with that of the toxic metal during EDTA treatment and secondly, the chelation of the ionic calcium in the blood, that can cause tetany and even death, can be avoided by administering the chelator as the calcium salt. 

---