What are ion channels?
Proteins that form pores in the plasma membrane
What are ion channels categorized by?
- Gating mechanism
- Ion selectivity
- Pharmacology
Are ion channels passive or active?
Passive
What determines the direction of flow through an ion channel?
- Concentration gradient
- Electrical gradient
Excitable cells are (negative/positive) on the inside and (negative/positive) on the outside
negative; positive
Potassium is (high/low) inside and (high/low) outside the cell
high; low
Sodium is (high/low) inside and (high/low) outside the cell
low; high
The membrane gradient is maintained by active transport of ___ out and ___ into the cell and by channels that selectively permit ___ to run out of the cell at voltages near the resting membrane potential
Sodium; Potassium; Potassium
Calcium is (low/high) inside and (low/high) outside the cell
low; high
Which ions do not cross the cell membrane?
Negatively charged
What is Kcsa?
A H+ gated K+ channel from bacteria
What is MthK
A Ca++ gated K+ channel from bacteria
How do CCB’s cause vasodilation?
Block channels in vascular smooth muscle
What are the therapeutic uses for CCB’s
- Decrease BP
- Relief of angina Pectoris
- Antiarrhythmic
How do CCB’s cause their antiarrhythmic activity?
Block channels in cardiac muscle ans SA/AV node
What causes vascular smooth muscle contraction?
Ca++ induced Ca++ release
Extracellular calcium is required for contraction of what muscles?
Cardiac and vascular smooth muscles; NOT skeletal
What can CCBs be used for clinically?
- Angina Pectoris
- Arrhythmia
- HTN
What are the three chemical classes of CCBs?
- Dihydropyridines
- Phenylalkylamines
- Benzothiazepines
Which CCB does not have reflex tachycardia secondary to vasodilation?
Amlodipine
What is verapamil’s inhibitory effect on the heart due to?
Frequency dependent block
