Cardiovascular 1 Flashcards
Where is Ca2+ stored in higher concentrations?
intracellular stores such as ER/SR and mitochondria
What are the 3 ways in which cytoplasmic Ca2+ levels are regulated?
a) Ca2+ entry mechanisms
b) Ca2+ extrusion mechanisms
c) Ca2+ exchange between ER/SR and cytosol
What are the 3 Ca entry mechanisms?
1) voltage-gated Ca channels
2) ligand-gated Ca channels
3) store-operated Ca channels
What is the mechanism of voltage gated Ca2+ channels?
open when cell is depolarized
What are the different types of voltage gated Ca channels?
N and P = neuronal (involve NT release)
L = heart and smooth muscle
Which drugs inhibit voltage gated Ca channels?
- VERAPAMIL
- DILTIAZEM
- DIHYDROPYRIDINES (DHPs), e.g. NIFEDIPINE
Which drug is used to treat hypertension? What is the mechanism?
DIHYDROPYRIDINES –> inhibit voltage-gated Ca channels
Which drug is used to treat angina and supraventricular arrhythmias?
VERAPAMIL and DILTIAZEM –> inhibit voltage-gated Ca channels
What is the mechanism of ligand-gated Ca channels?
opened by NTs or other agoinsts
Which ligand-gated channel in neurons is highly permeable to Ca2+?
NMDA glutamate channel
Which ligand-gated channels are considered to be the only true ligand-gated ion channel in smooth muscle?
ATP-gated P2X channels
What is the mechanism of store operated Ca channels (SOC)?
key: Ca2+ -release-activated Ca2+ (CRAC) channel
- intracellular stores depleted –> STIM1 accumulate at locations where ER is juxtaposed to the plasma membrane –> physical interaction opens CRAC channels
What are the 3 Ca extrusion mechanisms?
1) plasma membrane pump (PMCA)
2) SERCA pump
3) Na-Ca exchange (NCX)
What is the mechanisms of PMCA?
pump cytoplasmic Ca2+ out of the cell
What is the mechanisms of SERCA pump?
pump cytoplasmic Ca2 into ER/SR