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The resting concentration of Ca 2+ in the cytoplasm is normally maintained around 100 nM.This is 20,000- to 100,000-fold lower than typical extracellular concentration. [1] [2] To maintain this low concentration, Ca 2+ is actively pumped from the cytosol to the extracellular space, the endoplasmic reticulum (ER), and sometimes into the mitochondria.
Like strontium and barium, as well as the alkali metals and the divalent lanthanides europium and ytterbium, calcium metal dissolves directly in liquid ammonia to give a dark blue solution. [20] Due to the large size of the calcium ion (Ca 2+), high coordination numbers are common, up to 24 in some intermetallic compounds such as CaZn 13. [21]
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] 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. [10]
These are distinguished by using either Ba 2+ or Ca 2+ as the charge carrier in the external recording solution (in vitro). The CGI component is attributed to the binding of the Ca 2+-binding signaling protein calmodulin (CaM) to at least 1 site on the channel, as Ca 2+-null CaM mutants abolish CGI in L-type channels. Not all channels exhibit ...
Store operated calcium entry (SOCE) is used to regulate basal calcium, refill intracellular Ca 2+ stores, and execute a wide range of specialized activities. STIM and Orai are the essential components enabling the reconstitution of Ca 2+ release-activated Ca 2+ (CRAC) channels that mediate SOCE. Palty et al. (2012) reported the molecular ...
In thermodynamics, an activity coefficient is a factor used to account for deviation of a mixture of chemical substances from ideal behaviour. [1] In an ideal mixture, the microscopic interactions between each pair of chemical species are the same (or macroscopically equivalent, the enthalpy change of solution and volume variation in mixing is zero) and, as a result, properties of the mixtures ...
Calcium-activated potassium channels are potassium channels gated by calcium, [1] or that are structurally or phylogenetically related to calcium gated channels. They were first discovered in 1958 by Gardos [who?] who saw that calcium levels inside of a cell could affect the permeability of potassium through that cell membrane.