8/18/2019 Relevance of Intracellular Calcium
1/5
The intracellular Ca2+ is sequestered into
intracellular organelles;
mitochondria, endoplasmic/sarcoplasmic reticulum (ER/SR),
nucleus,lysosomes, and olgi apparatus! These structures pro"ide
#oth aninternal Ca2+ regulation and distri#ution system, and a
sca$old %or thesynthesis, targeting, and insertion o% channels and
receptors!
&arathyroid hormone, calcitonin and ', 2 dihydroy"itamin *,
and some
systemic (thyroid, se steroid, glucocorticoid) hormones or
humoral%actors (cytoines, groth %actors) are in"ol"ed in the
regulation o% the
Ca2+
le"el in #lood and in #one meta#olism!
The most a#undant mineral in the #ody!
Recommended intae o% calcium is approimately '---
mg/day, this requirement increases during childhood
groth,lactation and pregnancy!
Regulates many cellular processes
.as important structural roles in li"ing organisms! Seletal
muscle structure and %unction, polymeriation o% 0#rin 1ecessary
%or conduction o% impulses in the ner"ous system!
n important intracellular messenger in protooa, plants,
andanimals!
Regulation o% the ionic concentration o% calcium in "arious
compartments #ased on physiological demand is carried out
#ycalcium transporting systems located in the plasma mem#raneand in
the organelles! These systems upregulate calcium entry#y the action
o% se"eral hormones and calcium #indingproteins!
Cellular calcium plays an important role in apoptosis! The
accumulation o% calcium can induce "arious apoptoticpathays in
the cell!
Cytoplasmic calcium (Ca2+) concentration modulates cellular
%unctions, such as gene epression, meta#olism,
proli%eration,secretion, neural ecitation and %ertiliation!
3pening o% calcium in4u channels increases the cytosolic
calcium concentrations! .oe"er, high calcium concentrationsare
toic to the cell! .ence calcium is rapidly remo"ed %rom thecytosol
#y calcium pumps and echangers!
Ca2+ homeostasis is also "ery important in the aging
process,
cancer, heart disease, and muscle and neurodegenerati"ediseases,
as ell as descent o% the testis!
Calcium
8/18/2019 Relevance of Intracellular Calcium
3/5
$*,$T- T)$PH,PHATE "$P.# and /A09&= and * are produced
hen the T&7 comple %ormed hen *& isechanged %or
T&!T&7 comple acti"ates phospholipase C hich in turn acts
on mem#ranephosphatidyl inositol 7B, #isphosphate (&9&2)
producing * and 9&=!9&= increases intracellular
calcium #y li#erating calcium %rom calcium
stores and #y opening calcium channels!9&= is the ma:or
second messenger that causes Ca 2+ release %rom
internalstores
&hospholam#an, also non as &H1 or &H, is a protein
that in humans isencoded #y the &H1 gene! 9t is %ound as a
pentamer and is a ma:orsu#strate %or the c6&7dependent protein
inase (&8) in cardiac muscle!9t is an inhi#itor o% cardiac
muscle sarcoplasmic reticulum Ca2+7T&ase(SERC) in the
unphosphorylated state, #ut inhi#ition is relie"ed
uponphosphorylation o% the protein! Dhen phospholam#an is
phosphorylated#y &8 its a#ility to inhi#it the sarcoplasmic
reticulum calcium pump(SERC) is lost!
8/18/2019 Relevance of Intracellular Calcium
4/5
CH63*IH91 calcium #inding protein! Dhen #ound to Ca2+, itJs
capa#le o% acti"ating di$erent calmodulin7dependent inases lie;
phosphorylase inase, pyru"ate inase and myosin
light chain inase hich phosphorylates myosin hich #rings a#out
smooth muscle contraction! lycogen synthase, glyceraldehyde7=
phosphatedihydrogen, pyru"ate dehydrogenase, isocitrate
dehydrogenase, pyru"ate car#oylase, adenyl cyclase, guanylate
cyclase and 13 synthase!
Ca2+/calmodulin inases 9 and 99 are in"ol"ed in synaptic
%unction and Ca2+/calmodulin inase 999 is in"ol"ed ith protein
synthesis! cti"ates some enymes through calmodulin7calcium
comple!
Calmodulin7calcium comple also regulates acti"ity o% structural
elements associated ith smooth muscle contraction and
micro0lamentmediated process lie endocytosis, cell motility,
mitosis, release o% secretory granules etc!
![Mechanism Chest pain andthe hyperventilationsyndrome some … · [ ] =intracellular concentration, e.g. [Ca2+]It increased intracellular concentration of ionized calcium. LVDP=Left](https://img.pdfslide.us/doc/110x75/5e9803b4cc7cc5780210ca6f/mechanism-chest-pain-andthe-hyperventilationsyndrome-some-intracellular-concentration.jpg)
