Regulation Of Intracellular Calcium (session 2) Flashcards

1
Q

What is the extracellular [Ca2+]?

A

Approx 1-2 x 10-3 M

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2
Q

What is the cytoplasmic [Ca2+]?

A

Approx 1 x 10-7 M

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3
Q

What is the ER/SR [Ca2+]?

A

Approx 2-3 x 10-4 M

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4
Q

What causes an increase in cytoplasmic Ca2+?

A

Movement of Ca2+ across plasma membrane

Release of Ca2+ from ER/SR

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5
Q

What decreases cytoplasmic Ca2+ conc?

A

Relative impermeability of plasma membrane to Ca2+
Pumps and transporters that move Ca2+ out of cytoplasm
Ca2+ ‘buffer’ proteins (Ca2+ binding proteins)

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6
Q

Describe the mechanisms that decrease [Ca2+]

A

ATP-dependent mechanisms:

  1. Plasma membrane Ca2+ ATPase (PMCA)
  2. SR/ER Ca2+ ATPase (SERCA)

Transporter mechanisms:
1. Na+, Ca2+ exchanger (NCX)

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7
Q

Describe the mechanisms that increase [Ca2+]

A

Ca2+ movement across plasma membrane (influx)

  1. Voltage operated Ca2+ channels (VOCC)
  2. Ligand gated ion channels (LGIC)

Ca2+ movement out of ER/SR (release)

  1. Ca2+ induced Ca2+ release (CICR)-ryanodine receptors
  2. IP3R
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